As stated earlier in this blog, my intention is to create a facsimile of Jaguar's unique XJ13 - as it was in 1966/67 and before it was rebuilt in 1972/73. It had to be rebuilt after it was badly damaged on the eve of its first public appearance in 1971. My aim is to recreate the car as faithfully as I am able and as a tribute to the genius of its designer, Malcolm Sayer.

During the rebuild by Abbey Panels in 1972/73, certain aspects of the car were altered and it lost its "pure" form as originally envisaged by Sayer. One of the more obvious "enhancements" was the addition of flared/widened wheelarches. The XJ13 log records this was done primarily for "cosmetic reasons". Earlier entries in this blog describe some of the major differences between the car I want to recreate and the car as it stands today.

Undoubtedly, the current car is unique and has continuous history linking it back to the one and only original. It may have been described as a, "Jaguar-built replica" by authors Viart & Cognet in their 1985 book, "Jaguar - A Tradition of Sports Cars" (page 318), with forward by William Lyons himself, but I personally feel this may be a little unfair as most of the underlying structure was salvaged and re-used (with the exception of certain floor and sill sections - the original sections were originally painted black and are likely to have been been replaced). The engine installed in the car today is a different engine to the one originally installed in the XJ13 in the Spring of 1966 but it remains one of the very few prototype quad-cam engines that have survived and was installed in the car in period. OK, the body may be completely new, and different in some respects to the original body, but there can be no doubt that the car gracing the Jaguar Heritage collection can describe itself as the unique Jaguar XJ13.

What I am attempting to create can only ever be a facsimile and homage to the original XJ13 and its designer Malcolm Sayer. There is, and always has been, one Jaguar XJ13.

So - how to set about recreating a car which doesn't exist anymore?

Contrary to what you may read from certain replica manufacturers over the years, there are no "blueprints" for the car. Jaguar, on their part, have never allowed sufficient access to the car to enable detailed measurements to be made. Again, this is despite statements to the contrary by certain replica builders. Indeed, a replica made by the very talented Rod Jolley which passed into the hands of the late Jaguar Specialist Tim Waddingham, bears a brass plaque claiming the replica was produced "with the co-operation of Jaguar". The inaccuracy of the replica compared to the original bears testament to Jaguar's unwillingness to allow intimate access to the car. The closest anyone got to the car may have been Bryan Wingfield whose car eventually ended up in the Walter Hill Collection. However, this car was notoriously "wrong" in may details - including a rather "snub-nosed" appearance. The latter does indicate how difficult it is to replicate the complex curves of the car simply by reference to photographs - even with privileged access to the car itself and for a man with undoubted car-making skills.

OK - there are no "blueprints" and no chance Jaguar will allow sufficient access to the car so where do you go from here?

Fortunately, Jaguar Heritage very kindly granted me access to XJ13-related documents in their archive. However, although the archive is now professionally managed by Anders Clausager and his team, this has not always been the case in the past and many documents may have gone missing in the intervening years. Although Jaguar Heritage's archived documents give valuable clues to the car's build and history, I have had to dig deeper and extend my search further afield. A breakthrough came the best part of a year ago when a collection of original documents came to light containing actual data describing the original car's construction. This has since been supplemented by previously-unpublished photographs taken during the car's build in 1965/66. It is my wish to eventually deposit these documents in the Jaguar Heritage Archive for the benefit of future historians.

What are these documents exactly?

These documents contain critical measurements used by Jaguar to build the car. They are likely to have originated from Malcolm Sayer himself. Just to explain ...

Malcolm Sayer, as I reported in a previous post was very much a man “ahead of his time”. There is much talk nowadays of Computer Aided Design (CAD) and Computer Aided Manufacturing (CAM) but it seems that as early as the 1950s Sayer had developed his own longhand version of similar techniques. He kept his calculations and means of representing complex shapes mathematically very close to his chest and there is little information on his methodology available today. Paul Skilleter reported that Cyril Crouch, who worked in the Body Drawing Office in Sayer’s time, recalls him “using Chambers seven-figure log tables to calculate all the shapes, as one would do on a computer now.”

In essence, these documents consist of a mass of numbers defining fixed points in 3D space. For example, a particular single point on a body surface can be defined as:

As an example of data for one part of the car, the following original document indicates how the curvature of the windscreen was defined.

Original data - definition of outer windscreen surface.(Data obscured). © Jaguar Heritage - reproduced with permission.

At the start of my project I discovered that Pilkingtons claimed to have located the original metal jig used to manufacture the original 1966 XJ13's windscreen. (see earlier blog entry Triplex Laminated Windscreen. I commissioned a windscreen from them and this gave me a unique opportunity to objectively validate their claims against the original data. The finished windscreen was digitally scanned by Stuart Brown of 3D Engineering and it's precise shape was captured.

Digital scan of windscreen made using Pilkington's original XJ13 windscreen former.

Stuart then superimposed the 3D points defined in the original Jaguar document. He was then able to carry out a statistical comparison of the two sets of data. During this analysis he discovered that Sayer had defined the windscreen as sitting a rather strange 32.39 degrees from horizontal. The conclusion was that Sayer found, "wherever the windscreen laid within his overall body profile was correct". More detailed analysis by Stuart showed a close agreement between the windscreen Pilkingtons had produced and the original Jaguar data. The following picture shows the variance between points on the two defined surfaces - the closer to red, the bigger the difference:

Comparison of the new windscreen vs original Jaguar data.

The data is shown below:

In short, there is an average of 0.06mm difference between the new screen and the original data - pretty good don't you agree?

This was very good news for me as it meant we could precisely locate a key section of the outer body. But more was to follow .... similar data describing original car's body shape, as well as data precisely identifying key location points for things such as steering rack, front and rear suspension, suspension arms, shock absorbers etc etc was uncovered. The latter data has proved especially invaluable in the design and ongoing build of the complete chassis/monocoque unit.

Here is an example of the type of data that shows where key components are located. It shows the precise location of the XJ13's upper front wishbone (wishbone as used in the 1964 Lightweight E-Type Jaguar). I have obscured the actual 3D data points.

Original document describing location of upper front wishbone in 3D space.

The above data doesn't only describe exactly where the wishbone should attach to the chassis, it also gives valuable information on the dimensions of the chassis itself. Combining data such as this with original photographs such as the one shown below allows us to precisely model the front suspension. Whether or not we will choose to copy the rather poor quality of welding remains to be seen ....

Front chassis.

Putting all this data together, along with other measurement data and contemporary photos taken during the car's build have enabled us to arrive at an excellent digital CAD representation of the 1966 original. This data has been further enhanced by discussions with those who were present and participated in the original build.

So - where to from here?

All the above data has been used to enhance the digital model of the 1966 car. Gradually seeing the 1966 car emerge from the data has been a rather exciting process. The first physical manifestation of the digital data has been the manufacture of a full-size buck which is being used to manufacture the car's monocoque. Pictures of this buck can be seen in a previous post Building the Chassis/Monocoque. We have decided to build the monocoque in steel first, just to "get it right". This all-steel monocoque will then be destroyed and we will build one using original-spec aluminium and steel as original.

At the same time, work has been continuing on the buck which will be used to form the outer body panels. The picture below shows some views of the "virtual CAD buck" as it looks today.

Before I finally press "GO" and have the body buck manufactured, I have commissioned a pair of 3D-printed models of the body - one in 1:18 scale and one in approximately 1:30 scale. It is all very well being able to see the finished car on a screen but I wanted to have something I could hold in my hand. I plan to paint the larger of the two so I can see how the light catches it and how the curves measure up to the original. First impressions are very favourable

To be continued ....

Whilst researching people, places and events surrounding the XJ13 I came across references to the West Yorkshire Foundry.

Who are they ... do I hear you ask? For the best part of 100 years the Foundry was responsible for the casting of cylinder heads and blocks for the British automotive industry. Have a look on practically any cylinder head or block made in the UK in the last 60 years and the chances are you will see the initials "WYF" cast into the block and/or head. For example, the following initials are proudly displayed on my prototype quad-cam engine block:

Prototype V12 casting marks.

The West Yorkshire Foundry emblem can be seen as an intertwined "W" and "Y". The other characters refer to the material of construction (LM8), Jaguar's experimental identification (XW 5014) and Part Number (C2020). If you look at more recent Jaguar blocks, the West Yorkshire Foundry initials are even more prominently displayed as shown on this SOHC V12 block from the 1980s:

SOHC V12 casting marks.

The West Yorkshire Foundry has had an association with Jaguar from the days of the SS Jaguars right up to the first years of the 21st Century - not only supplying castings for Jaguar's production cars but also one-offs and small runs for things such as the initial run of 10 castings for Jaguar's "XJ6" quad-cam V12 engine project (not to be confused with their later saloon of the same name). The supplied bare castings for the racing engine project were delivered to Coventry Climax in 1964 for final fettling before being delivered to Jaguar's Experimental and Competition Departments for assembly and installation.

Watch almost any programme or film on TV and you will see something that was made by the West Yorkshire Foundry - Aston Martin, Rolls-Royce, Jaguar, Rover and many more.

Having found almost nothing in print about the West Yorkshire Foundry I set about trying to learn a little more about them and their association with Jaguar. I had visions of perhaps stumbling across casting patterns and records of correspondence between the Foundry and Jaguar - perhaps even from the times of Jaguar's Le Mans successes in the 1950s through to the XJ13 project itself? These initial hopes were soon dashed when I discovered the Foundry had quietly closed in 2004 with almost no trace of its former existence to be found.

This is what is found if you visit parts of the site of the foundry today:

The West Yorkshire Foundry today.

Even more poignant if you superimpose a picture of a group of workers on a picture of some of the remaining original buildings:

What had happened to all those moulds, patterns, drawings and historic correspondence? It seemed that nothing had survived. I continued my search and , at the start of 2010, came across a website - www.fettling.com. The website reads,

The book, "Meltdown" and DVD referred to above are available from: 

Heads Together Productions, The Media Centre, 7 Northumberland Street, Huddersfield HD1 1RL E: adrian@headstogether.org

Leeds Industrial Museum, Armley Mills, Canal Road, Leeds, LS12 2UF T: 0113 263 7861 E: www.leeds.gov.uk

Waterstones, Albion Street, Leeds, LS1 6HX T: 0113 242 0839

The Round Foundry Media Centre, Foundry Street, Leeds, LS11 5QP T: 0870 420 2300 E: info@roundfoundry.net www.roundfoundry.net

"Meltdown - Words and Images from a Yorkshire Foundry"

The book and DVD do provide a fascinating glimpse into the day-to-day life and individuals who worked at the Foundry. Thankfully, someone had the foresight to preserve at least some images. The website also provides a forum connecting past employees and my research continues with surviving foundry-workers (bearing in mind the prototype engines were made almost 50 years ago!).

For now, here are some glimpses into the last days of the Foundry as shown in the DVD. I don't know how many copies of the book are left of whether there is enough interest to justify a reprint but I do recommend you add a copy to your personal library while you still can. It is currently on sale for a very reasonable £10.

Here are some excerpts from the book that accompanies the DVD:

"The Clarence Road Foundry was part of Leeds' manufacturing heritage for many years. Its closure brought to an end another chapter in our industrial history.

Engineering is concerned with the transformation of energy and the manufacture of industrial engines and power driven appliances. Defined in this way, Leeds was a pioneering city in the late eighteenth and nineteenth centuries. Millwrights were the earliest mechanical engineers, concerned with such 'prime movers' as water mills and waterwheels. By 1820, the steam power revolution was well underway in Leeds, thanks to its textile mill owners harnessing their operations to the ideas of inventors like Thomas Savery (1650-1715), Thomas Newcomen (1663-1729) and, more importantly, James Watt (1736-1819)...

... by 1938, the derelict foundries in Sayner Lane were occupied by the Airdale Light Alloy Company ... one source suggests that the Airdale Light Alloy Company had been given a small contract to manufacture aircraft parts, but could not meet the Ministry's tight deaadlines; as a result MAP asked Leyland Motors to step in and manage the foundry ... there was a distinct shortage of carburettors for the Rolls-Royce Merlin engines, which powered both the Spitfire and Hurricane fighter aircraft, during the Battle of Britain ... Leyland sent a small team of foundry specialists to Leeds ... in March of 1942,... the total weight of carburettors produced was less than that of other castings. He (Mr West of Leyland) was beginning to feel his task was completed ... by the end of the war it is probably true to say that many, if not all the carburettor bodies flying for the RAF had been made in Sayner Lane ...

The last tank produced at Sayner Lane by Leyland Motors - © British Commercial Vehicle Museum

... the resurrection of the wartime foundry in Sayner Lane, Leeds, as West Yorkshire Foundries in 1846 is closely linked with the development of the British Motor Industry in the second half of the twentieth century ... between 1948 and 1951, domestic sales accounted for less than 30% of the output of private cars and only 45% of commercial vehicles. The British Automotive Industry had become one of the world's key exporters of motor cars. It was into this favourable economic climate that the foundry at Sayer Lane emerged as a manufacturer of high quality iron and aluminium castings for cars and commercial vehicles ... rumour has it that, after the war, MAP sold the Sayner Lane Foundry to Leyland Motors for one pre-decimal penny as a gesture of gratitude for the Company's efforts during the war ... by 1961, production at West Yorkshire Foundries had reacged 120 tons of aluminium per week and 600 tons of grey iron ... the physical expansion of the plant was enormous, growing from 7,300 square yards in 1946 to 48,000 square yards in 1961 ... The Company, by 1961, employed 2,000 people to make 14,000 different parts for the domestic motor industry ... West Yorkshire Foundries supplied most of the motor manufactureres in Great Britain with cylinder blocks and heads ... Jaguar bought over thirty separate parts for their specialist car market and headed a list of customers which reads like a Hall of Fame for British car manufacturers ... in 1966 ... the West Yorkshire Foundries built a new state-of-the-art gravity die-casting foundry ... the main Aluminium Sand Foundry was producing the six cylinder heads for Jaguar and Rover ... Walter West retired from the company in 1969, and left behind a prosperous and expanding business ...

1954 advert

... however, sooner than West or anyone else could have anticipated, the cold blasts of merger, rationalisation and recession would be whistling at the foundry doors in Sayner Lane ... in Britain, output of vehicles per employee per year became an embarrassing statistic. The British needed 67% more labour to make a Ford Escort than the Germans, and 132% more than the Belgians to make a Mini ... as a result of a series of mergers and acquisitions, in 1962, Leyland Motors Limited became the British Leyland Motor Corporation; operating on sixty different UK sites - West Yorkshire Foundries being one of them ... British Leyland faced a serious cash-flow crisis and were forced to turn to the Government of the day ... Leyland were in a fight for their very survival ... under pressure from Margaret Thatcher's 'belt-tightening' Government, Michael Edwardes announced a long-overdue restructuring of British Leyland ... following an internal review of management and staff, the future of thirty Leyland sites was still in the balance; West Yorkshire Foundries was one of them ... in 1982, British Leyland was renamed the Austin-Rover Group and the foundry at Leeds continued to act in a limited way as a supplier of high-cored cylinder blocks and heads to the automotive industry ... (in) 1985/86, West Yorkshire Foundries was sold to a private German company (Eisenwerk Bruhl) ... Yorkshire Foundries changed its name to VAW Motorcast Ltd and flourished after 1997 ... in 2002, West Yorkshire Foundries once more faced the prospect of new owners (later to become Hydro Aluminium Motorcast Limited) ... within eighteen months ... Hydro decided there was too much capacity in the automotive cylinder head and block market and a worrying lack of orders beyond 2004 ..."

Announcement by Hydro Aluminium Motorcast

... by 2005, the foundry buildings in which they (the workforce) and generations before them had laboured, would be silent, empty and unused ..."

It never ceases to amaze me just how many original parts and original unpublished accounts/documents still turn up for the XJ13/quad-cam engines after so many years. Recent discoveries have included a complete set of UNUSED inlet valves for the quad-cam heads as well as previously undiscovered photos taken at the time of the original build in 1965. I can add these items to the growing list of items that have surfaced - including an original-spec ZF "Dash 1" transaxle which was still in its crate from the 1960s. The transaxle is currently being rebuilt and will incorporate changes made by Jaguar for the original XJ13. This includes using a pair of ORIGINAL XJ13 driveshafts used on the XJ13 during its development. I need to research a little further but it is entirely possible these driveshafts were in place when David Hobbs set the UK closed-circuit record of 167.5mph in 1967.

The picture below shows the 1 7/8" "new-old-stock" inlet valves (in pride of place on a table in my living room - much to my wife's disgust ...)

"New-Old-Stock" V12 quad-cam prototype engine valves.

Two original high-resolution photos have recently come to light (the photos below are low-resolution for the web). They were taken during the build of the original in 1965 and give valuable details which will be faithfully incorporated in my recreation. The first shows the rear view of the monocoque and shows how the engine mounts were built up. A wooden "jig" can be seen which was used to locate the engine mounts. The left-hand sill is where the dry sump oil tank will sit. The large circular opening gives access to a rubber oil tank that sits inside the sill.

H1965/66 original XJ13 - rear monocoque

This second picture gives more detailed clues of the front monocoque construction. Note the similarity to the 1964 Lightweight E-Type.

H1965/66 original XJ13 - front monocoque

Here is a picture from a little while ago of the heads which will become the valves' new home. The heads have been stripped, thoroughly examined and skimmed by a few thou. Pressure-testing confirmed the heads' integrity. All guides are within tolerance and the valve seats were found to be securely fixed in place. The guides and seats will not be replaced although two exhaust valves (very slightly out of true) and all valve springs will be replaced.

Heads stripped for inspection.

How is the body coming on do I hear you say?  Here is a sneak preview of the millimetre-perfect outer body as a digital image.

Body surfaces - 1966 XJ13 (as intended by Malcolm Sayer and as originally constructed)

The next picture shows how the digital model compares to the 1966 original. The most striking feature is how Malcolm Sayer's original XJ13 design in the wheelarch area follows a similar pattern to the D and E-Type (rather than the "1970's flared arches later added by Jaguar).

Body surfaces - compared against 1966 original.

On Friday, 16th December 2011 a small group gathered around the XJ13 at Jaguar Heritage to mark the launch of Peter Wilson's book, "XJ13 - The definitive story of the Jaguar Le Mans car and the V12 engine that powered it".

This was no ordinary gathering, as those present included many surviving members of the team that were originally involved in the original XJ13 car as well as the development of the engine that powered it. Those present included Norman Dewis, George Buck, Frank Philpott, Jim Eastick, Ron Greves, Mike Kimberley, Roger Shelbourne, Robert Berry, Peter Taylor and Peter Wilson himself.

Click the images below to see videos and more detail of the proceedings

The videos include introductions by Tony Duckhouse (on behalf of Jaguar Heritage), Paul Skilleter (renowned Jaguar author and publisher) and further insights by Mike Kimberley (XJ13 Project Manager - later to join Colin Chapman and become CEO of Group Lotus):

More details of the book itself are available from Paul Skilleter Books or the Jaguar Clubs of North America.

As the build of the "trial" all-steel monocoque/chassis progresses, I wanted to consider the materials that should be used for construction of the component parts of my final version. Jaguar themselves went through a similar exercise in 1964 when the XJ13 had reached an advanced design stage.

Before then, in the few years leading up to 1964, various studies/reports were made on things such as the shape of the overall body, the design of the underlying chassis structure and suspension design. One, quite advanced, design was for a rather more integrated monocoque design as shown in the following sketch from the November of 1963:

Early monocoque design for the XJ13.
© Image - reproduced with permission.

However, the above design was not progressed further and, instead, a separate monocoque/chassis unit was developed which was to be clothed by a largely unstressed outer skin:

Representation of original XJ13 monocoque/chassis.

In essence, the final design for the monocoque/chassis consisted of three main elements:

The design of the front suspension went through a few different incarnations as the car was being assembled. Derrick White, Jaguar's talented Race-car Engineer argued for a cutting-edge design (for the time) using widely-spaced upper and lower wishbones. This would have given better handling and a greater possibility of maximising the benefit of the wider tyre widths which were increasingly being used in the mid-1960s. His persistent arguments were repeatedly blocked by Bill Heynes who favoured a more tried-and tested production-based suspension. Heynes eventually prevailed and a design, based on the 1964 Lightweight E-Type was adopted - albeit with coil-over shocks in place of torsion bars.

This decision was one of the things that led to Derrick White becoming increasingly frustrated and his eventual defection to Cooper - a great loss to Jaguar. White went on to design the GP-winning Cooper-Maserati of 1966. Heynes, at the time, had been given direct supervision of the XJ13 project and it has been argued that his enormous workload at the time contributed to the slow development of the XJ13. Fortunately, Mike Kimberley was eventually given day-to-day responsibility for the car and development then continued at a greater pace.

Meanwhile, in 1964 when the car had reached an advanced design stage - on paper at least - Jaguar conducted an investigation into the best materials of construction for the chassis/monocoque. They considered mild-steel, aluminium and titanium. The investigation concluded:

In the end, the chassis sections coloured yellow/green in the drawing above were fabricated from mild-steel. The main centre section was fabricated from aluminium.

According to Peter Wilson, who actually lent a hand in constructing the XJ13:

The modern equivalent, Aluminium 5251 (NS4), is available and will be used for the recreation along with steel pressings where appropriate. I must admit to some relief that Jaguar didn't choose titanium

For those engineers amongst you, and those well-versed in the mysteries of things such as Young's Modulus (I certainly don't include myself here!), the following summarises some of the data presented in Jaguar's investigation into material choice:

As is well-known, there is no such thing as a chassis that doesn't flex, but some are much stiffer than others. The choice of material is critical in this respect. The range of chassis stiffness has varied greatly over the years from about 500 lbft/degree in the 1930s to more than 20,000 lbft/deg in a modern race car. I should be able to measure the stiffness of my completed chassis and it will be interesting to compare the all-steel "trial" chassis to the final version.

Different chassis designs each have their own strengths and weaknesses. Every chassis is a compromise between weight, component size, complexity, vehicle intent, and ultimate cost. And even within a basic design method, strength and stiffness can vary significantly, depending on the details. There can be no such thing as the "ultimate chassis" for every car, because each car presents a different set of problems. The XJ13 chassis gave a whole new challenge because of the intention to mount the engine as a fully-stressed member - with the whole of the rear suspension hanging off the engine/transaxle. I believe this would have beaten Colin Chapman's Lotus by a few years had the XJ13 actually raced. Jaguar carried out a number of theoretical investigations into how well the car should stand up to the torsional loads applied to the chassis because of this arrangement and the final rear chassis design took these anticipated loads into account. The front suspension arrangement bears many similarities to the E-Types with steel tubing attached to the front bulkhead and Jaguar will have built up much experience of this design.

It may seem that an aluminium chassis was always the logical choice, but this is not necessarily true. Aluminium is more flexible than steel or titanium. Indeed, the ratio of stiffness to weight is almost identical to steel, so an aluminum chassis must weigh the same as a steel or titanium one to achieve the same stiffness. Aluminium has an advantage only where there are very thin sections where buckling is possible. This certainly applies to the large sill and floor sections.

In the end, the "unintended crash test" crash at MIRA in 1971 demonstrated better than anything else the soundness of Jaguar's basic chassis design. Although there was considerable damage to the outer structure, the basic chassis/monocoque survived almost intact. More importantly, the legendary Test Driver, Norman Dewis, survived unscathed.

A question often asked of me is,

"How many prototype V12 quad-cam engines were built by Jaguar and where are they now?"

As I reported on this blog back in May 2010, the answer is SIX. Of this six, only three progressed beyond test-bed stage and were installed in cars. A seventh engine was assembled as a 60° V8 and run on Jaguar's test bed. The V12 block for this engine was converted into a V8 using a special crankshaft with throws for only eight of the twelve cylinders. There were plans to assemble an eighth engine but it never reached the test bed stage.

The above has now been confirmed by XJ13-expert Peter Wilson in an excerpt from his forthcoming book which appears in the November 2011 issue of "Jaguar World". I can now add further confirmation of these facts from a collection of previously unknown and unpublished original documentation. These documents were in the personal collection of the late Claude Baily - the architect of Jaguar's quad-cam V12, their legendary XK engine and quad-cam 90° 8 litre V8 amongst others.

Jaguar's Claude Baily.

Claude Baily joined the SS Jaguar drawing office during the second World War and his engineering talents were soon exploited by Jaguar. Baily became intimately involved in Jaguar's plans to replace their pre-war engine designs with a new generation of engines designed to power their latest saloons. He is perhaps best known for his part in the design of the legendary XK twin-cam engine.

Claud Baily's appointment letter.
© Copyright Tony Bailey (WPO Communications) - not to be reproduced without permission.

Spending long war-time nights fire-watching in a small office above the assembly tracks in Coventry, in the company of William Lyons, William Heynes and Walter Hassan, the architecture of the world-beating XK engine was laid down. The new engine was required to reliably provide a minimum of 160bhp, have a long service life and be refined in operation. Before the end of the war, a number of experimental single-cylinder and full engines were evaluated. The following original document from 1941 is likely to relate to one such experimental engine. J.A.Prestwich was better known by its initials "J.A.P." whose engines were used in many famous motorcycle marques and early aeroplanes. Customers included Morgan, Triumph, Brough Superior, AJS and HRD.

12th December 1941 - letter to SS Cars referring to experimental engine.
© Copyright image - not to be reproduced without permission.

4, 6, 8 and 12 cylinder configurations were all considered at this very early stage but it was the 4 and 6 cylinder versions that were finally adopted. It has to be said that the BMW 328 engine played an important part in formulating the architecture of these engines. Indeed, Heynes was great friends with an owner of a 328, Leslie Johnson, who loaned his 328 to SS Cars for evaluation.  Johnson was a British racing driver who competed in rallies, hill climbs, sports car races and Grand Prix races. Johnson's car was highly developed and had raced pre-war. In my opinion, the styling of the XK120 owes much to the BMW. A BMW saloon was also acquired by SS during the war and was fitted with one of the early experimental engines (the "XG"). Walter Hassan used this car as his own personal transport for an extended period for evaluation. One of Jaguar's own 2.5 litre SS Saloons was also used for testing the prototype engines although most of the development work was carried out on the test bed.

3.5 litre experimental XK engine - drawing produced to calculate compression ration.
© Copyright image - not to be reproduced without permission.

Left to right - Walter Hassan, William Heynes, Claude Baily.
© Copyright image - not to be reproduced without permission.

Heynes and Baily applied all their thoughts on engine design to the XK engine although they later commissioned Henry "Harry" Weslake to help optimise their design. Jaguar already had a long association with Weslake, a cylinder head specialist who had been instrumental in modifying the side valve standard engine used in the first SS sports car. He also worked on the larger SS engine. It is believed he was involved in the design of every Jaguar engine up to and including the V12 of the early 1970s.

Harry Weslake - © Copyright image - not to be reproduced without permission.

The following Weslake report gives a fascinating insight into his evaluation methods and his closing summary bears testament to the soundness of the XK basic design. Weslake concludes:

".... The engine has stood up remarkably well through these series of tests. The valve gear has remained quiet throughout, there has been no sign of variation in oil pressure and the engine improves in power out-put the longer it runs. The tests have been very severe, particularly the distribution ones, but never once was any mechanical trouble experienced. It is suggested that some breather attachment should be developed in order to keep a small depression in the crankcase so that oil corrosion can be minimised and this would also help to stop oil leaks, particularly in the valve chest covers ..."

© Copyright image - not to be reproduced without permission.

© Copyright image - not to be reproduced without permission.

© Copyright image - not to be reproduced without permission.

© Copyright image - not to be reproduced without permission.

© Copyright image - not to be reproduced without permission.

© Copyright image - not to be reproduced without permission.

© Copyright image - not to be reproduced without permission.

The camshaft drive was by duplex roller chain - an arrangement that was carried forward to the quad-cam V12 prototype engines. This arrangement was used in the first engine installed in the XJ13 as well as the second engine built and tested in a Mk.10 Jaguar. The "genetics" of the XK engine could clearly be seen in the later quad-cam V12. The following page of sketches (made by Claude Baily around 1949/50) clearly show how he was formulating a suitable cam drive for a quad-cam engine. It is believed the sketches were produced as a precursor to designing and building a quad-cam 8-litre 90° V8 engine for a post-war military application. A similar architecture found its way into Baily's quad-cam V12.

Baily's drawings showing his ideas for a quad-cam duplex chain drive
© Copyright image - not to be reproduced without permission.

Claude Baily had been working on a quad-cam 60° since 1949/50 - perhaps earlier. By the February of 1951 a fully-working engine may have been running on the test bed. This 12-cylinder engine was later developed as an 8-cylinder variant for military use. The following quad-cam V12 performance data was recorded on the 19th February 1951.

Claud Baily's 1950/51 60° quad-cam 8-litre V12 engine performance data.
© Copyright image - not to be reproduced without permission.

The following picture shows Baily's data in his own hand. Was this an estimate/conjecture or are they figures actually recorded on the test bed?

Claud Baily's 1950/51 notes.
© Copyright image - not to be reproduced without permission.

In 1962, Baily was given the go-ahead to develop his design as a 5 litre V12 to challenge at Le Mans. Although primarily designed for racing, consideration was also given to using the engine in production cars. At least two years before the go-ahead, Baily's 60° V12 engine was being proposed as a future Jaguar engine with a range of possible capacities as the following memo from Claude Baily to William Heynes demonstrates:

5th December 1960 memo - "POSSIBLE FUTURE RANGE".
© Copyright image - not to be reproduced without permission.

The quad-cam V12 engine project was given the code "XJ6" - not to be confused with the saloon of the same name. "XJ6" followed on from "XJ5" which was the code name given to the Mk10 replacement (eventually to become the 420G). Two Mk.10 cars (XJ5/4 and XJ5/5) were to become mules for the production variant of the "XJ6" racing engine. The following memo confirms that six prototype engines were being developed.

25th November 1964 memo - "12 CYLINDER ENGINES".
© Copyright image - not to be reproduced without permission.

The first two engines (XJ6/1 & XJ6/2) were first assembled to almost identical specifications which included dry-sump lubrication and Lucas mechanical fuel injection. In April 1966 XJ6/1 was installed in the XJ13. The second engine, XJ6/2, was installed in a Mk10 Jaguar (XJ5/5 - manual gearbox) on 14th April 1965. It was converted to wet-sump lubrication although its Lucas fuel injection system remained. After six months of testing in the Mk.10, XJ6/2 was removed from the car and reunited with a dry sump for further test bed development. In March 1966 it's dry sump was again converted to enable fitment in a second Mk.10 (XJ5/4 - automatic gearbox). By this time it had acquired a sextet of SU carburettors. It ran for almost 35,000 miles in this car before it was removed and replaced in XJ5/5. It was finally removed from the latter car and placed on the test bed for further development/testing until it was put into store in March of 1969. It remained as a complete engine until I acquired it in 2010. It is now being rebuilt to its original specification and will be placed in my replica of the 1966 XJ13.

So, to answer the question "How many quad-cam V12s were built and where are they now?" SIX quad-cam V12 engines were built.

XJ6/1 The first quad-cam V12 built but only the second to leave the test-bed and be installed in a car (XJ4/1).  Damaged in 1967 and retained as a spare by Jaguar. 

XJ6/2 The second quad-cam V12 built and the first to be installed in a car (XJ5/5) Survived as a complete engine and sold by Jaguar in the mid 1970s. Currently under restoration to original specification (same build spec as XJ6/1).

XJ6/3 Only ever ran on the test bed in a variety of configurations. Has not survived.

XJ6/4 Built using cast iron block and ran on test bed. Has not survived.

XJ6/5 Internally modified to run as a V8. Ran on test bed for a short while in 1965. Surviving components are with a collector in the US.

XJ6/6 No records exist. It is believed this engine was never actually assembled.

XJ6/7 Built to trial a die-cast "open-deck" engine block.  Installed in XJ4/1 (XJ13) to replace its original engine when damaged in 1967. Remains in the car to this day.

XJ6/8 Built to competition spec with ultimate development of cylinder heads but never left the test bed. Cannibalised whilst in storage in 1969. Cylinder heads placed on XJ6/2 which remain with it until today. The engine block found its way into an XJ13 replica built by Bryam Wingfield for the collector Walter Hill. 

It is interesting to note that Jaguar's XJ13 currently has a die-cast block that differs from its original XJ6/1. This die-casting process is used to reduce costs and will have been more relevant for a production as opposed to competition engine. The following letter indicates the target casting weight of a V12 block (OXW 5620 is an experimental part number current at the time of quad-cam testing)

Die Casting Quote.
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The XJ13's rather poor power to weight ratio when compared with its likely Le Mans competitors may have contributed to this attempt to lighten its weight?

As Mike Kimberley recorded after a test of the XJ13 at Silverstone in 1967:

BHP per lb weight

Ferrari P4/ .210

Lola Chev/ .207

Ford Mk4/ .206

XJ13/ .177

It is also interesting to note that the engine currently installed in the XJ13 has a single OPUS 12 cylinder distributor. Its original engine, XJ6/1, as well as XJ6/2 were fitted with twin 6-cylinder distributors.

XJ6/2 Original twin distributors as originally fitted to XJ6/1.
© Neville Swales.

XJ13 single 12-cylinder distributor on XJ6/7 engine.
© Neville Swales.

The rebuilt XJ6/2 will, of course, be built using its original twin distributors. In 1966 Claude Baily was charged with pricing the OPUS system. The following letters give an interesting insight - comparing the various options under consideration.

© Copyright image - not to be reproduced without permission.

© Copyright image - not to be reproduced without permission.

© Copyright image - not to be reproduced without permission.

There are other differences between the XJ13's original engine (XJ6/1) and the one currently installed in the car (XJ6/7). One is the inlet manifold throttle bodies. The first photo shows the original (1967) arrangement with dual throttle bodies (and separate mounting plates - coloured yellow) and the second shows the current arrangement (photo taken 1973) with individual throttle bodies and a single mounting plate on each head. Note also the different cam cover treatment - the earlier engine has the "trademark" polished cam covers wheras the currently-installed engine has a crackle-black finish.

1967 (original car)
© Copyright image - not to be reproduced without permission.

1973 (rebuilt car)
© Copyright image - not to be reproduced without permission.

Background

Work has finally commenced on building up the chassis/monocoque of my recreation of the 1966 Jaguar XJ13 - a "snapshot" of the car as it was in 1966 before it was crashed and modified. Almost 18 months of painstaking and exhaustive research has revealed details of the original 1966 car which will hopefully allow us to recreate the car as Malcolm Sayer intended - without the later "1970's" modifications/enhancements.

Research is still ongoing and takes advantage of recent, previously-unpublished, documentary finds as well as details soon to be revealed in Peter Wilson's forthcoming book - the definitive story of the XJ13 and the quad-cam engine that powered it. Peter's book is scheduled for launch towards the end of November 2011. A tantalising glimpse is available on Paul Skilleter's website.

Peter Wilson book - "XJ13".

Piecing together details of the original car has been an exhaustive and a very time-consuming process. Originally centred around the relatively few original documents that have survived as part of Jaguar Heritage's archive, research was supplemented by face-to-face and written communication with surviving ex-Jaguar employees. Chief amongst these is Peter Wilson (Jaguar Competition Department 1961 - 1966). Since leaving Jaguar, he has worked in a number of prominent and senior positions in the automotive industry including time spent Brico Engineering, Cummins Diesel Engines and British Leyland. Since his retirement in 1999 he has written the definitive work on the Competitions Department between 1961 and 1966 including not only the XJ13, but a significant era in the racing and development of the E-Type. I can heartily recommend Peter's book "Cat Out of the Bag" which is available from Paul Skilleter books at www.paulskilleterbooks.co.uk. Others have included the Jaguar automotive electrician Bryan Martin who actually wired up the original car and applied all those "temporary" red dynatape stickers (which still "grace" the car almost 50 years later ...).

Another invaluable resource has been Norman Dewis himself - not only from his numerous recorded interviews and recollections but face-to-face discussions at Jaguar Heritage. I am the proud owner of a personally signed copy of Norman's autobiography "Norman Dewis - Developing the Legend" which contains some facts about the XJ13 - the whole book is a fascinating read.

Norman Dewis' Autobiography - "Developing the Legend".

The work of creating the car has been entrusted to North Devon Metalcraft - a long-established family-run company manufacturing high quality, complete steel and aluminium motor bodies and replacement panels. ND Metalcraft was founded over thirty years ago by the father of John and Paul Evans who run the company today. Their late father was a time-served craftsman with experience stretching back to the 1950's. As well as being a Freeman of the City of Coventry he handbuilt the first London Black Cab. He passed his skills on to his sons Paul and John and now ND Metalcraft are best known for their body/chassis work on the Shelby Cobra, Jaguar, Aston and Triumph TR. The quality of their work is beyond reproach and I am confident in their ability to deliver an absolutely authentic 1966 XJ13 copy.

North Devon Metalcraft.

North Devon Metalcraft - XJ13 monocoque buck in the company of an Aston and Triumph.

As I researched the original XJ13 it very soon became apparent that there is no such thing as an original XJ13 blueprint, construction plans or drawings. To make matters worse, Jaguar have never allowed anyone close enough to the XJ13 to take detailed measurements for the purposes of manufacturing a replica. Replica manufacturers who claim they have had privileged access to the XJ13 are not being truthful. Others who say they have copies of original manufacturing plans are telling lies. Testament to this are the number of inaccurate XJ13 replicas currently in existence - to be truthful, I have yet to see a replica that accurately replicates the current car - and I have seen lots in the last 18 months!

The detailed information needed to reconstruct the original 1966 XJ13 has had to be pieced together from original drawing fragments, original Malcolm Sayer 3D measurement data, period photographs and the surviving remains of the original car.

Very early photo of the 1966 XJ13 clearly showing original lines of front and rear wheelarches.

It has to be remembered that the car currently in the Jaguar Heritage Collection differs in many respects from the 1966 original. Although many components such as the engine, instruments, chassis/monocoque, bonnet lid etc survived the crash intact, it is unlikely that original components such as the windscreen would actually fit the rebuilt car's body and there are numerous differences in the body form - some subtle and others rather more substantial (such as later 1970's flared wheelarches and the overall length of the car).

Crashed XJ13.

However Jaguar's XJ13 does provide clues to be able to "peel back" changes made in 1972/73 and reveal many features of the original car. For example, evidence of where the crumpled remains of the original body was cut away from the monocoque and how the new body/outer-sills were attached can be seen in the following sequence of pictures:

The following original 1965/66 photograph (reproduced with permission) shows the original sill in place in the car. The TIG weld and breather(?) holes are highlighted in yellow.

Photo of original 1965/66 monocoque. (The more eagle-eyed of you may notice the dash panel instrument layout differs to that in the current rebuilt car as well as their E-Type origins).

A separate panel is riveted to the floorplan (highlighted below) and meets the folded-over sill along the TIG weld. I suspect this panel had to be separate because a row of rivets attaching it to the floorplan can clearly be seen when the car is viewed from underneath (it would not have been possible to place these rivets if the sill/floor was formed from a single sheet of aluminium and folded back over itself to meet the floor).

Photo of original 1965/66 monocoque.

The car suffered substantial damage to its sills during its crash in 1971. Indeed, Norman Dewis' account of the crash suggests a sill may have made contact with a sand-filled oil drum. The following photo of the rebuilt car gives evidence that the outer sill was replaced and joined to the upper sill cover at its outer edge. The join was masked by the door rubber sealing trim and was roughly pop-rivetted into place.

Sill detail - rebuilt car.

Use of 3D Reverse-Engineering

A major contributor to the project has, and continues to be, Stuart Brown of 3D Engineers. Without these cutting-edge reverse-engineering techniques, the ability to produce an absolutely authentic and accurate replica would have been severely compromised.

Stuart Brown scanning original quad-cam V12 engine.

What is 3D Engineering?

In simple terms, 3D scanning is a fast and supremely accurate method of putting physical measurements of an object onto the computer in an organised manner, resulting in what is commonly called 3D scan data. Typically, the 3D scan data is represented with a scale digital model or a 3D graphical rendering. Once the scan data is on the computer, all of the dimensions of the physical object can be taken, such as length, width, height, volume, feature size, feature location, surface area, etc. This even extends to being able to calculate things such as centre-of-gravity, suspension clearances, how well various components such as radiators etc will fit in the final car etc.

Components that are known to have been used in the original XJ13 can be scanned in this way and added to the 3D scan data. This includes things such as the windscreen (made using original tooling), E-Type rear light clusters and front suspension components.

In general, a device that captures 3D information from a physical object is referred to as a 3D scanner. There are many different methods for capturing the 3D measurements of a physical part and thus, many different types of scanners. Stuart himself makes use of various scanners including an OptiNum 3D optical scanner.

Stuart Brown of 3D Engineers trying his hand at wheeling an aluminium panel under the watchful eye of John Evans of ND Metalcraft. The verdict was that "Stuart should stick to what he is best at - 3D Engineering ...

Because the 1966 XJ13 doesn't exist in its original form it has been necessary to supplement the digital scan data with data from other sources. Even if Jaguar made the rebuilt XJ13 available to us for scanning (unlikely in the extreme!)it would be of little value to us because it differs from the original 1966 car. One of the major sources of this 3D data for the 1966 XJ13 are documents containing measurements made in 3D space originally by Jaguar - possibly Malcolm Sayer himself. As Peter Wilson describes in his book "Cat Out of the Bag", Bob Blake built the original XJ13 by starting with a baseboard marked out with 10" squares. Malcolm Sayer's design was translated into 3D measurements by recording various points in 3D space relative to the baseboard markings. For example, the left-hand steering rack inner ball joint was defined as being 24.330" from the zero line on the baseboard, 17.320" perpendicularly up from this and 14.740" from the baseboad centreline.

Location of left-hand steering rack inner ball joint in 3D space.

I have obtained a large number of original key measurements such as this which precisely identify the location of key components such as front and rear suspension, monocoque/chassis dimensions etc. All of these critical measurements have been incorporated into Stuart's digital representation of the car.

The first task is to recreate the 1966 monocoque chassis - as was the case when Bob Blake picked up his first piece of aluminium and pondered Malcolm Sayer's measurements in 1965. The following picture shows the original XJ13 monocoque in the process of construction in 1965/66. If you look very closely at the bottom right of the picture it is possible to make out the 10" x 10" squares drawn on the baseboard.

Original 1966 XJ13 - chassis/monocoque construction detail - reproduced with permission.

This second picture is a representation of what the finished monocoque/chassis will look like.

Representation of original XJ13 monocoque/chassis.

We decided to produce two major buck/formers for our recreation - one for the chassis/monocoque and a second for the body itself. The following pictures show a digital representation of the chassis/monocoque buck followed by its full-size version. The central section and bulkheads are removable and will be replaced by the body buck when the chassis/monocoque is complete and we are ready to start work on the body. The plan is to first build a basic monocoque using sheet steel before committing ourselves to a full monocoque built using original-specification aluminium. I plan building a total of two full aluminium monocoques.

According to Peter Wilson,

The modern equivalent, Aluminium 5251 (NS4), is available and will be used for the recreation along with steel pressings where appropriate. This attention to detail will extend to the choice of aviation-quality rivets as original (I have seen too many oversize rivets used in replicas!)

Chassis/Monocoque - digital image.

Chassis/Monocoque buck.

The XJ13 used E-Type front suspension using coil-over shocks in place of torsion bars, vented discs and specially-manufactured calipers. All of these components will be used with modifications as per original.

Paul (ND Metalcraft) identifying data points on bulkhead from original Jaguar XJ13 data.

The front of the sills/floor. A "trial monocoque" being constructed using sheet steel. Once we are happy with the details we shall work using the rather more expensive original-spec sheet aluminium. I shall end up with a complete surplus steel monocoque before we begin building the final aluminium version. I don't know what I shall do with it yet - any offers/suggestions?

Rear view. The cross-hatched section will be removed. Note the width of the sills - seems I will have to lose some weight to fit in! The original cockpit is rather cramped (as is the cockpit of the rebuilt car).

"Trial" Chassis/Monocoque - side view.

To be continued ...

The XJ13 first ran in April 1966 and, by the summer of 1967, development was still continuing apace with an extended test at Silverstone in August of that year. This was the ninth test carried out over a period of less than six months which does demonstrate Jaguar's commitment to the project at that time. These tests were carried out with the full knowledge of Jaguar's senior management with test reports widely distributed internally by the project leader - Mike Kimberley.

Michael J. Kimberley (“Mike”) C.Eng., F.I. Mech. E., F.R.S.A., F.I.E.D, F.I.M.I has had a remarkable career in the motor industry over the last 56 years, working with some of the great engineers, innovators and leaders of the worlds motor companies. Mike started as an apprentice with Jaguar in 1953 before rapidly progressing to becoming in Section Leader, Special Projects at Jaguar in 1965 where he lead the team developing the Jaguar XJ13 Le Mans car, under such famous names as Jaguar founder Sir William Lyons and Jaguar race director Frank (Lofty) England ...."

Mike Kimberley - Jaguar XJ13 Project Leader.

During this active development phase it seems that most of the testing was carried out by David Hobbs with additional drives by Richard Attwood and Norman Dewis.

It was David Hobbs who set the closed course record (167.5 MPH) for UK with the XJ13. This record lasted for 19 years. Hobbs' first race was in 1959 driving his mother's Morris Oxford. He turned professional in 1964 and raced extensively world wide for 30 years. His last race driven was the Masters Championship in 1993.

David Hobbs - racing driver and former Jaguar apprentice. Picture taken at the 2009 Motorsports Hall of Fame Induction.

Richard Attwood was born in Wolverhampton, Staffordshire. Richard James David "Dickie" Attwood (born 4 April 1940, Wolverhampton, Staffordshire) is a British former motor racing driver. During his career he raced for the BRM, Lotus and Cooper Formula One teams. In his whole F1 career he achieved one podium and scored a total of 11 championship points. He was also a successful sports car racing driver and won the 1970 24 Hours of Le Mans race, driving a Porsche 917.

Richard Attwood - racing driver and former Jaguar apprentice.

Norman Dewis is Jaguar's legendary Test Driver. Dewis is best remembered for a career spanning 33 years at Jaguar. In the words of Paul Skilleter,

Norman Dewis - Jaguar's legendary test driver.

A quick search of the internet will uncover the commonly-held view that it was an impending change to Le Mans engine capacity regulations alone which led Jaguar senior management to halt further development of the car. However, the truth is perhaps a little more involved than this and it seems a number of factors may have conspired to halt further development of the XJ13.

• An impending change to the Le Mans regulations to limit engine capacity to 3 litres. In Lofty England's own words, in a memo to William Heynes, he stated "... the 3-litre maximum engine capacity formula for Group 6 prototype cars will be applied to all sports car championship races, which includes Le Mans, for the next three years, i.e. up to and including 1970, which period coincides with the remaining period of the current Formula 1 racing car regulations ..."

   

• The spectre of the "GT40 Armada" in 1967. In the spring of 1963, Ford heard that Enzo Ferrari was interested in selling his company to Ford. Ford committed millions of dollars researching and auditing Ferrari's company only to have Ferrari unilaterally withdraw from talks at a late stage. This angered Henry Ford II who directed his racing division to find a company that could help them build a Ferrari-beater on the world endurance-racing circuit. The Ferrari-beater turned out to be the Mark IV GT40 which, although american-built, was based on a collaboration between Ford and England's Lola. Ford did not, at this time, have the racing prowess to take on the likes of Ferrari so had earlier engaged in discussions with England's Lotus, Cooper and Lola - eventually choosing the latter as a partner.

   

• The BMC takeover of Jaguar. On 11 July 1966, the "merger" of Jaguar with the British Motor Corporation was announced. In reality, this was a takeover by BMC of Jaguar, but Sir William Lyons maintained control of most of his his empire. One reason that Lyons agreed to the 'merger' was to get financial backing for future model programmes. Lyons saw Jaguar's future success lay in introducing new road cars. Jaguar's finances were stretched at the time and racing had reached a new level of professionalism and expenditure that Lyons could not now justify.

On the 29th September 1967, Lofty England said:

The fact that Jaguar were actively considering a 3 litre version of the XJ13 indicates it wasn't this rule change alone that would have prevented them racing. England's other comments in the same memo give an indication of the real reason development of the XJ13 was shelved:

In other words, reading between the lines, not only would development of a competitive car be very expensive, it would also have to compete against the equivalent of then-current Formula 1 cars. It would have seemed very unlikely that Jaguar could have triumphed under those circumstances. Finances, since the BMC takeover, were tight and Lyons' emphasis would have been on new production models - not racing - especially not where Jaguar would stand little chance of winning.

The decision was made - late in 1967 - to stop active development of the XJ13 and emphasis switched to a V12 engine for the future lineup of road cars.

It is interesting to see what might have been if a 3-litre version of the XJ13 had been developed. Would it have been along the lines of one of Malcolm Sayer's drawings from around that time?

3 litre successor to the XJ13?

The time has come to consider the specification for the rebuild of the quad-cam V12 engine. The first important thing to consider was the means of driving the four camshafts.

As stated previously on this blog, the intention is to recreate an EXACT copy of the XJ13 as it was in its heyday in 1966/67 - WITHOUT its subsequent modifications which include its "delightful" 1970s-style flared wheelarches, alloy wheels and gear-drive to the cams. Contrary to common belief, gear-driven cams were not installed in the car until 1978 - a good 11 years after the project had been allowed to die. The XJ13 NEVER ran with gear drive to the cams in period - the cams were always driven by duplex chains. My original engine has duplex chain drive to the cams - as was the case with both engines originally installed in the XJ13.

This "gear-driven cam" myth became widespread by the publication of cutaway drawings such as the ones shown below. Indeed, Jaguar themselves began to believe their own myth.

Cutaway drawing of engine fitted to XJ13 in 1978.

Detail of partial gear drive to cams - part chain and part gears.

The confirmation that the XJ13 never ran with gear-driven cams in period can be found in Jaguar's own archive. The archive contains a series of engine test logs - a log for each of the six prototype engines assembled as quad-cam V12s. Of these six original engines, only three survived as complete units(although a fourth was subsequently built up from new and used parts left over at the end of the project and used by Bryan Wingfield in a XJ13 copy for the late Walter Hill). Two of the three engines remained with the XJ13 and I have the third. As well as these engine logs, a number of original reports and other documents have survived. The facts recorded in these documents can be used to accurately chart the progress of these engines. A good 45 years have elapsed since the project commenced and people's recollections of events all those years ago may be a little hazy - even those who were directly involved at the time. It is for this reason that I base my conclusions purely on the documentary evidence.

The logs confirm the XJ13 never ran with gear-driven cams in period as follows:

1. Only two of the six prototype engines have ever been installed in the XJ13. These are recorded as "No.1" and No.7".

2. The first engine to be installed in the XJ13 was "No.1". This unit was NOT built to competition spec and did NOT have geared cam drive.

3. After a spell of testing on the test-bed (conducted by Mr J Eastick) "No.1" was installed in the car in April 1966 - " ... engine handed to Mr Brookes for installation in XJ13 rear engined car..."

4. In the meantime, "No.7" engine was being developed on the test bed. This engine - No.7 - HAD been assembled with gear-drive to the cams. " ... 12/8/65 ... built to competition specification ...". Later that year, in December while the engine was still on the test bed, the timing gear on "No.7" engine was replaced by the timing gear from the "No.4" engine. " ... timing chain brackets, chains, sprockets, dampers from No.4 ...". "No.4" engine was the only V12 engine with a cast-iron block (the other engines were all alloy). "No.4" was not built to competition specification and had duplex chain drive to its cams. "No.4" may have been subsequently smashed up and has not survived.

5. For the remainder of 1966 and the start of 1967, the XJ13 continued its development powered by the chain-driven "No.1" engine. Meanwhile, "No.7"'s development continued on Jaguar's test bed with numerous references to the cam chain drive in its testing log.

6. On the 23rd April 1967 disaster struck! Norman Dewis missed a gear change at MIRA whilst testing - " ... unable to test for extended period. Dewis missed gear. Suspect bent valves ..." The XJ13's engine ("No.1") suffered extensive damage after the missed gear change. The "No.7" engine, still with chain-driven cams, was hurriedly prepared for installation in the car. On the 10th May 1967 "No.7" was removed from the test bed - still with chain-driven cams. Installation of "No.7" in the XJ13 commenced on 11th May 1967. "No.7" was recorded as still being in the car as late as July 1973 " ... engine in car for Silverstone demonstration run on 14/7/73 ...".

7. Meanwhile, "No.1" was returned to the test bed for further development/testing where it remained until 1978. In July of 1967, gear-driven cams were added to "No.1" while it was still on the test bed.

8. During this time, my engine, "No.2" continued to be developed both on the road and on the test bed. Indeed, it remained under development long after the other V12s had been removed/dismantled for storage. Development of "No.2" continued until 1969 when it was used to carry out comparisons with the road-car single overhead cam engine. It has the distinction of being the very first Jaguar V12 ever to run on the road and may have been the only engine to have reached the 502bhp @ 7500rpm falsely claimed for the engines installed in the XJ13. It is likely the maximum power developed by engines fitted to the XJ13 was a much lower 438bhp.

9. In 1978 disaster struck again ... " ... 3/7/78 (No.7) removed from XJ13 car after damage to 'A' bank cylinder head during warm-up for demonstration run at Daily Express March meeting. Engine known to have over-revved during missed gear change, would appear to be broken tappets or tappet guides, No.6 exhaust valve head broken off and jammed in seat ...". It was at this point, as late as 1978, the XJ13 was fitted with gear-driven cams for the first time - long after the project was dead, after its crash and after it had been "modified" for a life of demonstration runs only.

"No.1" engine remains with the XJ13 to this day.

In January of 2011, on a very cold January morning, the restoration of my quad-cam V12 began in earnest with a total stripdown and detailed examination. The task of rebuilding this important engine has been entrusted to David Butcher.

David can draw on his vast experience gained from many years of rebuilding Jaguar engines from the 1960s to date. He has had a long involvement with Jaguar engines since his days working alongside the late Ron Beaty at Forward Engineering. Although in "semi-retirement", David's skills are very much in demand today - particularly by racers and enthusiasts. David has worked on all variants of Jaguar's classic engines including the Group C and prototype Le Mans racers.

David Butcher starting work on the prototype V12.

We were privileged to be joined at the initial engine stripdown by Peter Wilson and Jim Eastick. Both Peter and Jim worked at Jaguar on projects associated with the XJ13 - Peter on the car itself and Jim on the prototype's V12 engines.

From left to right - Peter Wilson, David Butcher and Jim Eastick.

I was fascinated to learn from Jim Eastick that my engine has a direct connection with the legendary Ron Beaty as it was Ron who actually ran and optimised my engine on the Jaguar test bed. Beaty joined Jaguar and made his way up to being one of the all time greats at the works. He worked in the former competition dept and was experimental engineer for the V12. In the late 1960's Ron Beaty formed the company Forward Engineering which made him a household name in the Jaguar world, creating power units for British and world water speed records, Lister Jaguars (Beaty created the original Lister XJS with Brian Lister) as well as many track records both here and abroad. The original TWR XJS's were also "Forward " powered as were many small volume constructors like Panther. David Butcher worked alongside Ron Beaty at Forward Engineering and played an important role in some of Forward Engineering's various projects. Other notable "Forward Engineering Graduates" were Rob Beere and Carl Taylor of Rob Beere Racing.

While David worked on the engine, I was treated to an accompanying dialogue of recollections of life at Jaguar at the time of the project between Peter, David and Jim - memories sparked by details of the engine revealed as the stripdown progressed - recollections not only of the engine itself but also the many individuals involved at the time. Sadly many of these individuals are no longer with us. Jim also brought with him his personal notebook containing notes made while the prototype engines were actually being run on Jaguar's Test Beds - a book he kept very close to his chest!

Jim Eastick consulting notes made during prototype engine testing.

My engine was the second engine assembled and is believed to be one of only three engines surviving having left Jaguar as a complete engine. Two of the three engines remain with the XJ13. There is a fourth engine which was assembled from a collection of new and used parts left over at the end of the project and installed in a replica for the late collector Walter Hill by Bryan Wingfield. As the stripdown progressed it soon became clear that the engine was not only complete internally but was in quite remarkable condition despite its 40+ years of storage.

Head removal.

Jaguar's habit of liberally applying "Wellseal" to gasket surfaces was very much in evidence! Having removed the heads, the condition of the bores and pistons became apparent. Although there is slight surface oxidation on the crowns of the cast alloy pistons, this is to be expected on an engine that has been stored for this period of time. It does confirm that the engine has spent its last 40 years undercover and in dry conditions. The slight oxide buildup was only present on the pent-roof piston crowns and the remainder of the pistons was found to be in quite remarkably good and usable condition. The lack of any significant carbon buildup does tie up with the original testing logs which indicate the engine was only run for a short time on Jaguar's test bed before being removed for storage in December of 1969. The final bout of testing was for emmision comparisons with the SOHC production engine.

The cylinder block is a L.M.8 sand casting and has a sump face on the crankshaft centre line. This is in contrast with the later SOHC V12 which had a much longer "skirt" which helped increase block stiffness. The prototype engine is a solid casting as opposed to the die-cast "open deck" design of the later engine. This makes it a rather heavy engine which is difficult to manouevre by hand - ask me how I know!

Cylinder heads showing "tin" gaskets. In the foreground can be seen the original twin distributors. Twin distributors were used in the original 1966 XJ13 and were only replaced with a single "modern" V12 distributor during the car's rebuild in 1972/73.

Hemispherical combustion chambers.

The V12 cylinder head design is very similar to the 6-cylinder XK engine in basics such as valve operation with a few significant differences. In an attempt to arrive at a more compact and efficient combustion chamber, the chamber depth was reduced to 1.03" (from the XK's 1.30") and the included valve angle was reduced.

As explained by Jim Eastick, the V12 prototype engine has equal firing impulses along each bank and can be carburetted as an in-line 6 cylinder. The bore and stroke is 87mm x 70mm giving a displacement of 4991cc.

All prototype engines were fitted with twin 6-cylinder distributors. One of the many changes made when Jaguar rebuilt the XJ13 after its crash in 1971 was their replacement by a single 12-cylinder distributor. One of the two distributors, the "master", contained two sets of contact-breakers plus a centrifugal advance mechanism that served both distributors. The second distributor, the "slave", was simply a distributor for the H.T. current. My engine will be rebuilt with both distributors as original.

Jim Eastick explaining how he had added extra springs to the "master" distributor in an attempt to reduce points bounce during testing.

The heads on my engine are numbered 18 and 19. This confirms them as the ultimate development of the prototype cylinder head having an optimum subtended angle of 41 degrees to the valve axis with camshaft centres raised by 0.25". The cylinder heads remaining with the XJ13 may have never achieved the widely-reported maximum power of 502 bhp at 7,600 rpm achieved by an engine with this design of head.

The following picture shows the modified sump fitted to my engine. Although it is the engine's original racing dry sump, it was considerably modified in period to enable its fitment in the two Mk10 Jaguar "mules" for testing. The original gear scavenge/pressure in-sump gear pump was found to be in place but modified so that drive was transferred to a rear "wet-sump" pickup. The welded-up position of the original scavenge/pressure outlets can be seen at the front of the sump. The plan is to return the original sump to dry-sump specification.

Modified dry sump.

The four studs on the skirt of the block are used to not only mount the engine but also to provide a location for the rear trailing arms. There will be a corresponding pair of locating studs on the final sump. The engine/transaxle in the XJ13 supports the entire rear suspension.

Seen here is part of the duplex chain cam-drive arrangement - incidentally, as originally fitted to the XJ13 engines and not gear-drive as widely thought.

Chain-drive to cams.

The next few pictures show the sump being removed - revealing components not seen since the engine was assembled in Coventry in the late 1960s.

Preparing to remove the sump under the watchful eye of Jim Eastick.

Sump removed revealing combined scavenge/pressure pump and shaft used to transfer drive to the rear oil pickup. As with the later SOHC engines, a steel plate extends the full length of the crank.

Oil pump detail.

Chain drive to oil pump.

The engine has seven 3" diameter main bearings which means the later shells can be used (perhaps with slight modification to oil-holes). The big ends are unique which may cause some problems in finding replacements. When Jaguar recently rebuilt the XJ13's engine they found it necessary to increase the diameter of the conrod big ends to accept "off-the-shelf" bearing shells. This avoided a cost of something in excess of £20,000 to tool up for the prototype's unique bearing size. However, we have yet to fully explore whether or not the original size shells can be found. The crank pins are 2.187" diameter and are 1.20" wide to accept the side-by-side conrods. The conrods are offset 0.75" bank-to-bank. The crankshaft is made from forged steel and is lubricated using an end-to-end feed from grooves in the main bearings. The same sludge trap system as used on the earlier 6-cylinder XK engine was used with transverse oil feed holes. Although we have yet to confirm whether or not the crank was nitrided it is known that Jaguar used a EN 40 nitrided crankshaft in the competition V12.

David then began to remove the timing-chain cover so that pistons and crank could be removed.

Preparing to remove timing cover.

Timing cover removed.

The following picture shows detail of the lower two chains (four separate chains in total). One chain drives the oil pump while a second takes drive to intermediate sprockets - one for each head. Another sprocket is used to drive the twin distributors and Lucas fuel injection metering unit via a "Jackshaft". A hydraulic chain tensioner can be seen towards the bottom of the picture. The two top chains (driving the cams) are tensioned by an external nut applying pressure to a slipper.

The complexity of this chain layout was a factor in deciding to go with a SOHC layout for the production engine. The weight and cost could be reduced using a single chain drive with four sprockets compared to the prototype's four chains and twelve sprockets. Also, the noise level of the quad-cam layout was unacceptably high for a production engine. However, for racing purposes the quad-cam layout was preferred.

Timing chain detail.

Drive removed from oil pump.

Steel cover plate and scavenge/pressure pump removed.

Referring to original notes .....

Oil pump.

Removing slave distributor drive.

Distributor drive "jackshaft"

Piston sees light of day after 40 years.

All bearing shells were in remarkably good condition - confirming the engine's short time on Jaguar's test bed before the engine was removed for storage.

Journals also in good condition.

"Yours Truly" lends a hand.

Connecting rod still polished and shiny after all these years.

Preparing to remove crankshaft.

Jim Eastick remembering modifications to oiling system.

Detail showing "grooves" around oil holes on alternate big ends.

Slip-fit dry liners.

Crankshaft removed. Bearing shells were all in excellent condition.

Now that the engine has been stripped it can be given a detailed examination/measurement in readiness for its rebuild. As a matter of course things such as valve springs and (probably) valves will be replaced. After standing for more than 40 years it makes sense to replace items such as this - the thought of a detached valve in the rebuilt engine doesn't bear thinking about! Fortunately, we are well-blessed in the UK with skills and expertise to be able to build an engine such as this.

To be continued ...

As my quest to recreate an exact copy of the 1966 XJ13 continues, I came across the story of the man largely responsible for making the original body - Bob Blake. What follows is the story of a man able to translate the designs of people, such as the legendary Malcolm Sayer, into metal. Contemporaries of Bob Blake described him as "An Artist in Metal".

The late Bob Blake - 1916 to 2003.

Blake was born in 1916 at the Fort Totten Sioux/Dakota Indian Reservation, Elbow Woods, North Dakota, USA. The original Reservation at Fort Totten was located near Devils Lake. After 1905 almost half the land was sold to the Government and opened up for white settlement.

Fort Totten Indian Reservation.

The young Bob Blake took up panel beating as a hobby and was entirely self-taught. He taught himself to weld at the age of 19 and a lifelong interest in racing cars and their construction began.

After entering the services he visited the UK in 1942 with the US Third Army where he met his future wife, Jean. At the end of the war he returned to the US and set up a workshop building sprint and race cars - including midget racers. He didn't only make bodies, he also lent his hand to making parts such as chassis, fuel tanks, radiators, steering and almost everything else. As his skill and reputation grew, he progressed to work on Indianapolis cars for racers such as Ted Horn and Tommy Hinershitz. One of his early commissions was to manufacture parts for Alec Ullman's Alfa Romeo - Ullman, a Russian-born MIT graduate went on to found the Sebring 12-hour race in 1950 in an attempt to rejuvenate sports car racing in the US.

Bob Blake remained in touch with Ullman and received a phone call from him in 1950 during a visit to the UK. Ullman told him that Briggs Cunningham had entered two Series 61 Cadillac Coupe deVilles at Le Mans - one with a standard body and the second with a streamlined body. Howard Weinman, an aeronautical engineer, was tasked with streamlining the Cadillac. Weinman began by testing designs in wind tunnels. The resulting design was wide, had a low center of gravity, aerodynamic, and lightweight due to an aluminum body. Many people agreed that the appearance was not favorable and it received the name 'Le Monstre' by the French press. During preparations for the event, the standard car had been driven into the back of 'Le Monstre' and both needed urgent repair.

1950 Cadillac 'Le Monstre'.

Bob Blake immediately flew out to Le Mans and worked non-stop without sleep for 48 hours to repair the cars. He succeeded with only minutes to spare before scrutineering.

In the race, Cunningham and Phil Walters were the drivers of the 'Le Monstre'. The coupe was driven by Miles and Sam Collier. The traditional sprint start, where the drivers sprinted to their vehicles, revealed the doors were locked. The problem was able to be solved by reaching in through the window and unlocking the door - not a good way to start a race! On the second lap, 'Le Monstre' lost control and ended up in a sandbank where it sat for twenty minutes before Cunningham could dig it out. 'Le Monstre' was now four laps behind. The Coupe had a bit of misfortune as well. Part way through the race, it had to come to a complete stop while a stray dog made its way across the track. Later on in the race, it barely made it back to the pits due to low fuel. When the checkered flag fell, both cars were in impressive standing. 'Le Monstre' had battled its way back from 35th place to finish in 11th. The coupe was in 10th after averaging 81.5 mph per lap. To finish the race was a major accomplishment, a testament to both driver and car. Their accomplishment was even more significant since the Coupe had lost its first and second gears during the race.

Cunningham's ambition was to win at Le Mans with an American car and, to this end, set up a company in 1950 with Alfred Momo. Bob Blake's efforts at Le Mans had clearly impressed Cunningham and he employed Blake in his new company - giving Blake overall responsibility for building his Le Mans contenders. Bob Blake built every Cunningham car until the closure of the company in 1955. Although Briggs Cunningham never realised his ambition, he did come a creditable fourth in his Blake-built C-4R in 1952 and finished a respectable third in 1953 behind the winning Hamilton/Rolt Jaguar C-Type.

The Bob Blake-built C-4R on its way to fourth place at Le Mans in 1952.

Briggs Cunningham held Bob Blake in high regard and, when he closed his company in 1955, he wrote a glowing reference for the jobless Blake:

" ... He designed and built all our competition cars that raced at Le Mans from 1951 thru 1955, doing most of the work himself. He is one of the best aluminium welders and formers in the USA, and we found him invaluable in our racing department. Bob is a most efficient worker, and a real artist in sheet metal work of all kinds."

"His character is excellent, and his interest in his job profound. He loves racing cars of any kind, and is a wonderful man to have in the team at races, as he can make all manner of alterations and repairs very quickly, when the need arises. Bob was one of our most valuable team members, and I would highly recommend him to any firm or individual looking for one of the best body men in the world today. His loyalty is outstanding, and I frankly hate to lose him."

Bob Blake (far right) at Cunningham's company.

Bob Blake had come into contact with people such as Lofty England and other racing team members whilst racing with Cunningham and so was already known to them. In November of 1955 Blake joined Jaguar and began an association that continued for more than twenty years.

One of Blake's first responsibilities was to convert the stock of obsolete D-Type racers into road cars - the XKSS cars. He altered the D-Type body and added parts such as bumpers and hood frame. In his own words, Bob Blake said,

" ... I made all the frames and bits and pieces, including all the wooden tools to make everything from. I made the first set of bumpers by cutting down the big old bumper, using the top radius and the bottom radius, cutting the flute out and welding the two pieces together."

Jaguar XKSS - note the diminuitive bumpers that were to make a return in the E-Type.

Bob Blake was a likeable character who forged relationships with William Lyons and Malcolm Sayer amongst others. Bob worked very closely with Sayer and was able to decipher his mathematical representations of compound curves and produce panels from the data. Malcolm Sayer's way of working was a longhand precursor of the digital CAD techniques used today and he was very much a pioneer in this field. It is pleasing for me to realise that I am using today's equivalent of Malcolm Sayer's calculations in the construction of my XJ13 recreation. Sadly, neither of these two gifted individuals are still around to lend the benefit of their expertise.

After the XKSS, Bob Blake worked closely with Malcolm Sayer in the production of the first E-Type prototype - E1A. Indeed, Bob Blake went on to play a major part in producing the E-Type coupe. Working with an E-Type roadster, he tried different roof treatments within the Competition Department. He said, " ... I had a body in the Comp. Shop ... I took a whole mess of 1/16 steel rods and did a profile, a side elevation of the screen and the roof, flowing into the tail. I'd got all this tacked up and Sir William walked in the door."

"The Old Man looked at it and boy, he liked it. He fell in love with it the minute he walked in the shop. Lyons studied the mock-up for some time in silence, walking around it. He said to me, 'Did you do this, Blake?' I said 'yep'. He responded 'Its good. We'll make it!' "

Jaguar E-Type Coupe.

In 1962 Bob Blake became involved in the car that represented Jaguar's hope to return to racing - the Lightweight E-Type. Peter Wilson, in his book "Cat Out of the Bag" (available from Paul Skilleter Books at /www.paulskilleterbooks.co.uk) reports," .. It was early October (1962) when Bob Blake and Geoff Joyce started work on the first bodyshell. Malcolm Sayer, our aerodynamicist and designer of the D-Type monocoque, had meantime designed an aerodynamic package, consisting mainly of a special coupe top, with the combined objective of reducing both the aerodynamic drag and the frontal area. Malcolm's drawings contained no lines per se, but consisted of a matrix of dimensional points defined in three planes from a common base reference point, which defined the outer surface of the skin panel. His method was unique in the motor industry, but more commonplace in the aircraft design world."

"Malcolm claimed he had been taught this mathematical method of complex surface definition by a German, when they spent a few days together in a tent in the desert, during his time working in Iraq at Baghdad University, soon after the war. It was a system that was relatively easy to use; just a case of marking out the points defined by the co-ordinates on a sheet of plywood, cutting it out, then assembling each piece relative to its datum on to a wooden base and, 'hey presto', you had a complete skin former..."

Malcolm kept his method of mathematically calculating complex surfaces close to his chest ... from Malcolm's drawings, Bob and Geoff, together with Sam Bacon, built a wooden 'egg-box' former for the coupe skin."

Similar documents have survived - defining things such as the windscreen profile, suspension and steering points etc. Data from these are being incorporated into the digital model which will be used to manufacture a similar "egg-box" former for my XJ13 recreation.

Jaguar C-Type "egg-crate" body former.

"Virtual" buck for Bristol engined "special". Body designed by 3D Engineers - the company entrusted with the production of body formers for my 1966 XJ13 recreation.

In 1965 Bob Blake worked on the XJ13 project. His method of working is best described by Peter Wilson, " ... As our surface table was not large enough, or indeed remotely suitable, Bob Blake, Geoff and Roger built a rigid wooden platform on which to build the XJ13 monocoque ... First they constructed a perimeter wooden frame from a 6x4-inch timber, cross-braced at intervals along its length. This was topped with 3/4 inch thick plywood sheet, which they then marked out with '10' lines to enable accurate positioning of each of the myriad of construction reference points defined by Malcolm Sayer's 'drawings' "

" ... the monocoque was constructed almost entirely from NS4 2 percent magnesium and 2 percent manganese, half-hard alloy sheet, mostly of 18 swg thickness (0.048 inches), together with some sheet steel pressings in areas of high and concentrated stress, such as the main engine mountings and front suspension attachment areas."

" ... The floor section and outer sills were formed in two halves and were joined along the centre line of the car with an overlapping, joggled joint and a double row of rivets. The inner sill panels were made up and these, together with the internal half-rounded section inner sill stiffeners, four per side, were assembled to the floor section. At this point the whole job was shipped over to Abbey Panels at Exhall on the outskirts of Coventry for the inner and outer sill joints to be roller welded using their specialised equipment. ... This was then the sole contribution Abbey Panels made to the construction of the original monocoque. With this operation completed and the basic foundation of the monocoque firmly in place, construction proceeded apace with Bob, Geoff and Roger fabricating the majority of the panels and rivetting these in place, while the rest of us helped out with the simpler body items."

Peter Wilson talks of Bob Blake in his book, "Cat Out of the Bag" and Bob's personable character shines though. "... Bob Blake was a totally unique talent. He was a hands-on man, who also had a superb eye for style. Not only could he create a vision of shape and style, but he could then actually make it. He was the 'complete' body man and Jaguar were lucky to have his talents ... Bob was a super bloke, modest, self assured and always helpful. He did not suffer fools lightly and many is the time whilst I attempted some sheet metal work he would appear at my shoulder and say, 'Not like that you silly shit! Here, let me teach you how to do it properly.' And with great patience he would do just that."

Bob Blake in later life.

Rather amusingly, Peter Wilson talks of Bob Blakes "Secret Project". It seems that Bob Blake became rather more industrious than usual and was seen to be squirrelling various car components into the Competition Shop. The secret was eventually revealed to be his personal Ferrari project - a rather mangled 250 GT. The car was soon transformed by Bob into a beautiful blue car - complete with engine rebuilt at home by George Buck! Bob continued his interest in buying and repairing crash-damaged Ferraris and in the 1970s could be seen driving one of his three Ferraris - a 365 Daytona and two GTB 330s.

Described by his other contemporaries as a "delightful gentleman", Bob Blake retired to Northampton in 1978 with his wife and kept his hand in by fabricating small projects such as motorcycle fuel tanks for friends.

This talented key player in the story of Jaguar and the XJ13 passed away on 26th August 2003 at the ripe old age of 87.

Bob Blake's Ferrari Daytona.

As part of my research into the background of my prototype V12 engine, and as its rebuild looms (details to follow ...), I came across the story of a key man involved in its design - Walter T.F.Hassan, O.B.E.,M.I.Mech.E. What follows is the story of one of this country's most gifted designers of high-performance engines and a vital link in the XJ13 story.

Walter Hassan on his 90th birthday with fellow designers and veteran cars.

As previously revealed, the engine which will be installed in my recreation of the XJ13 is one of only three prototype engines originally designed by Claude Baily and developed by Walter Hassan and Harry Mundy which survived as complete units. Two of these engines are with the XJ13 and this third engine is presently undergoing a complete restoration to its original spec - a similar spec to the engine first installed in the 'original' XJ13. The most notable difference being that, wheras the engines originally installed in the 'original' XJ13 were not built to "full competition spec", the only surviving heads from the single engine assembled to this ultimate competition spec found their way onto my engine and remain with it today. This important engine represents a significant milestone in Jaguar's eventual V12 engine development - leading to one of the finest and most long-lived luxury car power units of recent years - a credit to the expertise of Walter Hassan. 

There is a "fourth" engine that was assembled from a collection of new and original parts left over at the end of the V12 engine project. This latter engine found its way into a Bryan Wingfield replica built for the late Jaguar collector Walter Hill.

There is no doubt that the quad-cam V12 prototype engines were all built primarily with racing in mind. As Walter Hassan wrote in his booklet summarising the development of the V12 engine:

It was clearly never the intention to install the quad-cam engine in a production car as, in Hassan's own words it would need to " fit into the same space as the six-cylinder engine without structural alterations to the body hull of existing models." The quad-cam prototype engine was too large and heavy to fulfil this role. Although my engine was installed in two Mk10 "mules" this was done as a means of further developing the quad-cam as a racing engine. In a filmed interview Hassan stated, " ... the engine was too big and noisy for a production car ...". (Click HERE to see the Hassan interview video). Soon after becoming involved in the V12 project, and after Jaguar took the decision not to race the XJ13,  Hassan began to formulate plans for a single-overhead-cam version more suited for road use.

Original 1976 booklet written by Walter Hassan for the Technical, Administrative and Supervisory Section of AUEW

Although the second engine built, my engine was ready for installation in a car long before the first engine because the latter encountered a number of problems during test-bed development as evidenced by the engine test records. The XJ13 car's development had been delayed and was not ready so my engine was installed in the first Mk10. The engine was installed in this car complete with Lucas mechanical fuel injection and modified dry sump (to clear the Mk10 cross-beam). By the time the engine was installed in the second Mk10 "mule" it had acquired a sextet of SU carburettors in place of the Lucas mechanical system. By all accounts, this produced an under-steering, nose-heavy, poorly-braking car with a limited turning circle (due to the width of the quad-cam engine) - albeit rather quick! This confirmed Hassan's belief that, although suited to racing, a more refined, lighter and more compact SOHC engine would be needed for road use.

But I am getting ahead of myself ... long before my engine's bark was heard in Coventry and was used to terrorise the Aston Martins on the M1 outside Newport Pagnell, Walter Hassan was taken on as an apprentice by WO Bentley. The year was 1920 and Hassan was a wet-behind-the-ears 15-year-old fresh from Hackney Technical Institute.

At this time, WO Bentley had only just moved into their first factory at the Welsh Harp Reservoir, Cricklewood in London. This area was rapidly becoming a centre of engineering excellence after the First World War had greatly stimulated industry in Cricklewood. Handley Page expanded considerably, and the French aircraft companies Caudron and Nieuport both had works in the area. In 1916 the School of Mechanical Warfare was set up in the fields between Dollis Hill Lane and Oxgate Lane as a proving ground for tanks. Amphibious tanks were tested in the Welsh Harp reservoir.

Women workers in an aircraft factory at Cricklewood during the First World War

the young Hassan's talents flowered very early on - in 1925 he prepared a Le Mans 3-litre Bentley for a 24-hour record attempt on the banked Montlhery circuit south of Paris, where it averaged over 95mph without problems. The special single-seater was built in 1925 to compete for world and international records at Montlhéry. It gained a World 12-Hour title in 1926 at 100.96 mph. WO Bentley himself described Hassan as, "very young, very keen and very ambitious".

1925 Bentley 3/4 1/2 Litre Le Mans Replica Tourer

It is reported that his "ambition" nearly cost him his life when Bentley returned to Montlhery in 1926 with the single-seater Bentley "slug" to attempt the first 100mph plus 24-hour record. "The works drivers, diamond millionaire Woolf "Babe" Barnato and jockey george Duller, had already covered over 1000 miles when Duller skidded on the banking. Shaken, he drove into the pit to allow Barnato to take over, but the "Babe" had gone off to eat, only the young Walter Hassan was present.
In his attempt to save the record attempt, Hassan leapt into the driving seat and drove off, managing only a third of a lap before the tricky handling of the "slug" sent the car skidding through the crash barrier. It rolled over, ending astride a ditch with Hassan apparently dead. "E's cooked 'is goose" a French bystander was heard to remark. The car was a write-off, and because Hassan was not a designated driver, any record would not have been officially registered anyway.
He recovered after three weeks in a private room in the American Hospital, Paris. It seems the fact that the hospital refused to accept any payment for Hassan's treatment endeared them to the "financially astute" WO Bentley.

The Hon. Mrs. Victor Bruce watches re-fuelling through the Le Mans style quick fill funnel during her record attempt at Montlhéry in June 1929.

In 1931, at the age of 26, Hassan joined the renowned Barnato who had pretty much funded Bentley since 1926 and was put in charge of Barnato's private garage at Ardenrun - Barnato's country house near Lingfield.

It was Barnato who, in 1930, accepted a challenge to race his Bentley against an express train, Le Train Bleu (the Blue Train) from Cannes to London. Barnato bet that he would drive his Bentley from Cannes to London and beat the train to Calais. After averaging 43.43mph during the 570 mile journey to Calais, Barnato crossed the Channel and finally reached the Conservative Club in St.James Street, London, beating the Blue Train to Calais by four minutes and winning his £200 bet.

Financier, motor racing driver and Chairman of Bentley Cars. Joel Woolf 'Babe' Barnato was born in Westminster, London, the son of Barney Barnato, an exceedingly rich man who made his fortune in the Kimberley diamond mines of South Africa.

Hassan developed a special 8-litre Bentley for Barnato - specifically for racing at Brooklands. Hassan used a 4-litre chassis frame which had assumed the identity of the 1929-30 6.5-litre Le Mans winner "Old Number One". The car crashed over the Brooklands banking in 1932 - killing its pilot Clive Dunfee. The car was subsequently rebuilt as a road car.

Portrait of Jack Dunfee and Woolf Barnato at Brooklands in 1929

Walter Hassan also created the Barnato-Hassan Bentley racer whose lap speed of 142.6mph was the second-fastest ever recorded at Brooklands. Hassan's achievements continued as he worked on the new ERA racing voiturette in 1936 after Barnato retired from racing.

In 1937 Hassan joined Thomson & Taylor of Brooklands. His main responsibility was to assist in the development of an advanced land speed record car designed for the legendary John Cobb by Reid Railton. It was Railton who told Cobb about the Bonneville Salt Flats and started the parade of LSR contenders to the Utah salts (then known as Salduro Salts). The year 1937 was a busy one, for Reid not only designed a Water Speed Record boat for Campbell that went 129.30 m.p.h, but an LSR car for Cobb based on 2 combined 1,250-b.h.p Napier Lion engines. The Napier-Railton captured the record in 1937, 1938 and 1947, and was the car that held the record longest in history, until the American assaults of the mid-sixties. Reid himself was at these runs; in fact, in 1939 he stayed in America, settling in Berkeley, California., and opening his new career by joining Hall-Scott Motor Co., makers of boat engines. He stayed with that concern, working on defense and war projects, through 1945, then quit to become a consultanr again. Among his first projects was readying Cobb’s pre-war car for the 1947 LSR attempt.

The Napier Railton on the track driven by John Cobb 1935.

It was in 1938 in the Brooklands paddock that Walter Hassan was approached by Bill Heynes of SS Cars. Heynes was looking for a chief engineer for his experimental department in Coventry. At the time, SS Cars were a rapidly growing company already selling 5,000 cars a year. In 1939 and the coming of the Second World War, Hassan turned his talents to developing carburettors for aero-engines at Bristol but returned to Jaguar in 1943 where he worked on scout vehicles which could be parachuted behind enemy lines.

In those final years of the war, while fire-watching in the company of William Lyons, Bill Heynes and Claude Baily, plans to introduce a new twin-cam engine were sketched out. At the end of hostilities, SS Cars was renamed Jaguar Cars. Hassan brought in an old friend from his Brooklands days - "Lofty" England - as Service Engineer. England was later to succeed William Lyons as Jaguar's Chief Executive.

The Jaguar twin-overhead-cam XK engine.

The new engine was finally unveiled to the public in the sensational 3.4-litre XK120 sports car at the London Motor Show in October 1948. For the first time, these cutting-edge twin-overhead-cam engines became accessible to the general public. The same basic design was employed by Jaguar for more than 40 years - a further testament to Hassan's talent.

Hassan's career didn't end there - he joined Coventry Climax as Chief Engineer and was instrumental in developing the legendary "FW" (featherweight) fire-pump engine into one of the most successful competition units of its day. Two specialised Grand Prix engines followed under Hassan's direction - the FPF 4-cylinder and FWMV V8. The FWMW began winning races in 1962 with Jim Clark. These engines went on to give Coventry Climax a staggering 96 Formula One victories and four world championships between 1958 and 1966. Stirling Moss scored the company's first Formula One victory in Argentina in 1958, using a 1.9-liter version of the engine. The FWE engine was also developed for the Lotus Elite and this enjoyed considerable success in sportscar racing, with a series of class wins at Le Mans in the early 1960s.

Coventry Climax FWMV 1500cc V8 Formula 1 engine in a Lotus 24.

Walter Hassan returned to Jaguar as director in charge of power units when Coventry Climax was purchased in 1963. He recruited Autocar's technical director Harry Mundy as Chief Development Engineer. In December of 1963 these two oversaw the assembly of my prototype engine - the first bark of this engine was heard in Coventry on the test-bed in January 1964.

I look forward to hearing Hassan, Baily and Mundy's remarkable engine roar once again ...... watch this space .....

On the 3rd June 1965 an internal "Instruction to Proceed (XJ13 Car)" was issued by Jaguar’s Bob Knight – it started, “Build one prototype competiton car …”. Responsibilities for all aspects of the car’s design were allocated – the responsibility for the body being given to Malcolm Sayer, Phil Weaver and Bob Blake.

The body was to be, “Light alloy skin on monocoque structure. Comprising of three main sections”. These three sections were:

• “Body Front Structure” (main skin, front bulkhead, headlamp diaphragms, air-ducts for radiator/brakes etc, internal structure to suit 1964 Jaguar Lightweight E-Type independent front suspension and a boot lid).
• “Body Centre Structure” (floor & sills, fuel & oil tanks, seat back bulkhead, doors and windscreen).
• “Body Rear Structure” (main skin, engine cover, spare wheel, cooling ducts for transmission & brakes, rear lid and rear valance).

Other responsibilities were allocated as appropriate. Rather telling was the comment “For the first car only” which does confirm the prototype XJ13 was planned to be one of many.

By the June of 1965, the quad-cam V12 engine project for the XJ13 was well underway – with the emphasis very much on racing. The first V12 engine to be fitted to any car was my engine (engine number 2) which was fitted to a car codenamed “XJ5/5” – XJ5 being the code name for the Mk10 successor. This engine was fitted to this sable-coloured “test mule” in April 1965 – complete with Lucas Mechanical Fuel Injection and modified dry sump - some two months before the XJ13’s “Instruction to Proceed” was issued. The engine in the “test mule” was built to the same specification as the first engine (number one) which was to be installed in the XJ13 a year later in April 1966.

Overall responsibility for the shape was given to the late Malcolm Sayer – the man already responsible for the Jaguar C-Type, D-Type and later to be responsible for the iconic designs of the E-Type and XJS.

Malcolm Sayer, 1916-1970

Malcolm Sayer was a student of aerodynamics at Loughborough University’s Department of Aeronautical and Automotive Engineering in 1938. He was one of the first designers to apply the principles of aerodynamics to cars with his scientific calculations, creating some of the most beautiful forms of the era. Sadly he died in 1970, at the relatively young age of 54.

After graduating from Loughborough he joined the Bristol Aero Company where he worked on various projects including their radial engine. One of Sayer’s colleagues at Bristol was Phil Weaver who was later to work to take charge of Jaguar’s Competition Department and work alongside Sayer on the XJ13. In an interview with Phil Weaver, Paul Skilleter (well-known Jaguar Historian and Author) recorded Weaver’s recollections of his time with Sayer at Bristol.

Malcolm Sayer joined Jaguar in 1950 and his talent was soon recognised. One of his first tasks was to design a suitable body for Jaguar’s XK120C (the “C-Type”). The chassis had already been designed by Jaguar’s Technical Director Bill Heynes. Sayer worked alongside Bob Blake who had been given the responsibility of producing a body. Sayer brought his aerodynamic skills to bear on the project and added a large element of science to the body design. He was one of the first to use wind tunnels in automotive design and photographs exists of the various small-scale models he had made to investigate the aerodynamic characteristics of his various designs.

Norman Dewis, Jaguar’s renowned Chief Tester, joined Jaguar not long after Malcolm Sayer and recalled how Sayer worked:

A number of contemporary sources cite Sayer’s habit of drawing a full-size car on the walls of his office or even with chalk on the floor. I don’t doubt that some of his initial designs for the XJ13 were done in this way. He had at least one small-scale model made up for testing before Bob Blake began the task of clothing the chassis/monocoque.

Sayer’s final designs were “formalised” as side, front, rear and plan view documents which may have become internal “standards” for his designs and used for things such as centre-of-gravity studies etc. The detail shapes of compound curves etc were established mathematically using a technique peculiar to Sayer.

Examples of these final standardised documents are shown below:

XJ13 “dimension summary”© Jaguar Heritage

In late 1967, after he had designed the XJ13, Malcolm Sayer designed three more V12 mid-engined sports racing cars. The drawing above shows one of these designs in the form of a “dimension summary”.copy; Jaguar Heritage

It is interesting to note that Sayer’s original design as shown above differs in many respects from the rebuilt “original”. It is my aim to reproduce the XJ13 exactly as Sayer had intended and before the addition of “1970s wide wheels/wheelarches” and other “updates”. It is important to me to recreate the car as close to its original specification as possible – not only to satisfy requirements for potential racing against cars of the period, but also because the historical significance of the surviving original prototype engine demands this. After all, Jaguar had always intended to produce more than one car and I feel an authentic copy could be considered to be a “continuation” in line with Jaguar’s original intentions.

Malcolm Sayer was very much a man “ahead of his time”. There is much talk nowadays of Computer Aided Design (CAD) and Computer Aided Manufacturing (CAM) but it seems that as early as the 1950s Sayer had developed his own longhand version of similar techniques. He kept his calculations and means of representing complex shapes mathematically very close to his chest and there is little information on his methodology available today.
Paul Skilleter reported that Cyril Crouch, who worked in the Body Drawing Office in Sayer’s time, recalls him “using Chambers seven-figure log tables to calculate all the shapes, as one would do on a computer now.”

Bob Blake had joined Jaguar from Briggs Cunningham and was a legendary body-builder. He was able to interpret Sayer’s data and successfully translated his drawings into the full-scale XJ13. He was joined in this task by Roger Shelbourne and Geoff Joyce. Peter Wilson also worked on the car and was responsible for making some components of the car and chassis. Wilson confirms that, contrary to popular belief, the original car wasn’t built by Abbey Panels – their involvement was limited to “the fabrication of skin panels to our formers, and roller-seam welding of the inner sill panels to the main floor and outer sill sections.”
Peter, in his book “Cat Out Of The Bag” goes on to say,

Much of this data has survived – including the precise location points of items such as suspension components, steering rack, anti-roll bars in 3D space. This data will be used in the construction of my 1966 XJ13 copy. The main difference being that technology allows us to carry out this operation on a computer screen before the actual car is manufactured.

To help achieve a faithful copy of the original design, the technique of 3D scanning coupled with digital techniques to incorporate data from period photographs, original technical drawings and eye-witness accounts is being used.
An example of how digital data can be built up from an original document (in this case an accurate drawing used in 1965 for a centre-of-gravity study) is shown below. The pictures show initial work on reproducing the original centre monocoque structure.

© Neville Swales
Not to be reproduced without permission.

© Neville Swales
Not to be reproduced without permission.

© Neville Swales
Not to be reproduced without permission.

This digital data can be supplemented and cross-referenced with original photographs, reports and original technical data – as well as the “original” prototype. Once the information has been captured, it is possible to estimate things such as weights, roll-centres, centre-of-gravity etc. It is also possible to virtually “trial-fit” components to reduce the possibility of an error during the actual build.

Once sufficient digital data has been assembled and the on-screen 3D images have been verified with photographs etc, the next step will be to use the data to produce a physical scale model using CAM techniques including the use of a 3D printer. The scale model can be painted in the correct shade of 1965 BRG (British Racing Green), handled and verified for accuracy. It also gives an opportunity to see how the light catches the car in comparison with period photographs and the current “original”. Once this has been accomplished, the digital data can be used to manufacture millimetre-perfect full-scale formers and bucks – even to the extent of pre-marked or drilled rivet locations.

As well as being able to use these powerful techniques to faithfully reproduce the original car, they can also be used to reproduce unobtainable and unique parts such as cylinder heads etc. The following picture shows this scanning technique in action on the prototype engine:

© Neville Swales
Not to be reproduced without permission.

The item to be scanned (anything from a small component to a full-size car) is covered in a non-reflective white powder. Small adhesive dots are applied across its surface and the item is laser scanned. The small dots allow the sophisticated software to locate specific points in 3D space. Internal passageways may be scanned using similar techniques using lasers on probes.

Manipulation of the resultant data and production of a final digital representation of the scanned item is a skilled operation. Once the item has been captured in this way, faithful clones can be reproduced using computer aided manufacturing techniques.

noun. Zeit·geist

… is a German word. Zeit meaning “time” and Geist meaning “ghost,” Zeitgeist means the spirit of the age or times.

Original 1966 XJ13 - MIRA 1971

The 1966 Jaguar XJ13 is no more.

Its spirit and identity live on in a Jaguar-built replica constructed from the mortal remains of the original car which suffered a calamitous crash during a demo run in 1971.

The event was a promotional exercise to publicise the soon-to-be-launched Jaguar Series 3 V12 E-Type. The venue was the high-speed banked track at the British Motor Industry Research Association (MIRA). The date was 20th January 1971.

In the words of Norman Dewis , Jaguar Test Driver, in his book "Developing the Legend

" ... "It was all the fault of the Series 3 E-Type and the new Hassan/Baily 'flat-head' production V12. The idea emerged that the new Jaguar V12 engine in the Series 3 E-Type should be launched to the press at Geneva in March 1971 amid the sight and sound of a previously unrevealed, mid-engined V12 Le Mans car emerging into sight from behind the trees. This involved getting the XJ13 out of hibernation, and as a backup to the press launch, a film would be made for wider distribution."

So it was that on 20 January 1971 a film crew from London met up with the XJ13 and Norman at MIRA.

XJ13 awoken from hibernation before that day in January 1971 Photo © Jaguar Daimler Heritage Trust

After being under wraps for over two years, the car had needed a complete check-over and, as the wheels it was on had done most of the development work, they were substituted by new wheels and tyres which had remained in the stores.”

Photo © Jaguar Daimler Heritage Trust

Break during filming Photo © Jaguar Daimler Heritage Trust

All went well at first, with a good number of laps put in at modest speeds for filming. “

“All went well at first …” Photo © Jaguar Daimler Heritage Trust

Then to conclude”, Norman relates, “I was asked if I could do four fast laps. I did three, and they were quite quick, although not as quick as I had gone in testing.”

"Then on the third lap I came onto the banking, which was the one opposite the tunnel banking where the film crew were, at about 135, and gave it full throttle to hold it in as usual. About two thirds of the way round the banking, the car lurched to the right and almost instantly went into the safety fence ..."

“... the car somersaulted off the track into the muddy field ... tyre tracks showed how the car had almost left the banked section ... then spun down the banking to end up in the field ...”

“ I was asked if I could do four fast laps. I did three, and they were quite quick ..” Photo © Jaguar Daimler Heritage Trust

The XJ13 Log Book simply states "20.1.71 Written off" at the top of the entry ..

Extract from XJ13 Log Book © Jaguar Daimler Heritage Trust

Luckily, the driving skills and lightning reflexes of the Jaguar test driver Norman Dewis meant that he survived the crash unscathed. He walked away from the crash having buried himself in the narrow confines of the cockpit. The state of the car was, however, a different matter …

The fact that the car survived at all to participate in this promotional exercise after development had ceased in 1967, was simply down to the fact that the Jaguar management felt it could play some part in promoting their production V12 engine. A memo from the late Lofty England to the late William Heynes in the September of 1967 outlines the reasons for shelving the XJ13 project as well as the justification for keeping the car in storage and not breaking it up as was the fate for many earlier projects.

“… we are about to commit ourselves for considerable expenditure with ZF for the supply of special gearbox units for the current XJ13 5-litre competition car and also a 3-litre version, which is a new project.

I feel I should point out that there now seems no doubt that the 3-litre maximum engine capacity formula for Group 6 Prototype cars will be applied to all sports car championship races, which includes Le Mans, for the next three years, i.e. up to and including 1970, which period coincides with the remaining period of the current Formula 1 racing car regulations.

There does not, therefore, appear to be any point in doing any further development work on the 5-litre car or, in fact, on a 3-litre version, unless it is our intention to produce a lightweight 3-litre Formula 1 type engine, as cars which will be competing in sports car championship races in the next three years will be in effect Formula 1 racing cars with bodywork to meet the sports car regulations. These regulations may well be amended in 1969, whereby it will no longer be necessary to provide a spare wheel or luggage accommodation, or have a specified windscreen height on open cars.

I suggest we ought to keep the 5-litre competition car as a complete unit, since we could possibly get some publicity value from it when we announce one of our production cars with a 12-cylinder engine.”

What caused the crash?

Norman Dewis confirmed that new wheels and tyres were added prior to filming. The XJ13 Log Book states these wheels were made new after testing of the car only four years earlier (late in 1967). Excepting possible manufacturing defects, it is perhaps unlikely that they could have deteriorated to the point of failure in that short space of time in storage? The use of magnesium as a constituent of alloy wheels was not a new technology in the 1960’s – indeed, magnesium wheels were used on every car that won the Indy 500 from 1946 to 1963.

When the tyres were fitted to the car’s new wheels in 1967, they were fitted without the benefit of inner-tubes. It is possible that the new tyres fitted before filming in 1971 were also fitted without inner-tubes. This, in itself, should not have caused a tyre failure. A more likely culprit may have been the unsubstantiated rumour that a rear tyre was “plugged” to prevent a slow leak before the final high-speed laps?

It is believed that the incident occurred at a speed below those attained during the short period of the car’s active development – although the speed may have been well in excess of 135mph it is unlikely the accident could have been caused by “lifting” or other “aerodynamic” reasons.

Another possibility could have been failure of a rear radius arm. Using the engine block as a stressed member, the rear wheels were mounted by a driveshaft (as upper link), a fabricated lower link and two forward-facing radius arms fixing directly to the engine mounting block. This was a rather innovative solution for the mid-1960s. Examination of the wreckage revealed a damaged upper radius rod on the rear right-hand side (offside)6. However, this damage could have been sustained during the impact. If not, a failure such as this could explain why the car “lurched to the right” before making contact with the safety-fencing at the top of the banking.

Perhaps the true facts and cause of the crash will never be known – the important facts are that the driver, the legendary Norman Dewis, and the car both survived.

What was the extent of the damage?

Except for occasional snippets of information, relatively little information has previously been made available on the development history of the XJ13 – this “vacuum” has been filled by a host of commentators/enthusiasts over the years with a range of statements and opinions – some of whom have probably never even seen the original car least of all been involved with Jaguar! As a consequence of this, an almost “mythical” status has been attached to the car. One therefore has to be careful when sifting through the “established facts”. Fortunately, at least one piece of original documentary evidence survives in Jaguar’s archive and that is the “XJ13 Log Book”. This book gives an account of the development and testing of the car including details of its post-crash examination. This document can be supplemented and cross-referenced, not only with other original surviving records, but by information from known and respected authors such as Paul Skilleter, Philip Porter, Andrew Whyte as well as surviving ex-Jaguar participants such as Peter Wilson, Mike Kimberley, Norman Dewis etc.

The XJ13 Log Book simply states "20.1.71 Written off" at the top of the entry ..

Extract from XJ13 Log Book © Jaguar Daimler Heritage Trust

In the words of Paul Skilleter in 1975 , “… there wasn’t a straight panel left on the XJ13 – a more written-off looking racing car you couldn’t imagine. It was a crestfallen party that took the remains back to Browns Lane and pushed it back into its dark corner of the development department.”

Back at Browns Lane the car was later stripped by G Gardner to assess the extent of the damage. It does seem that the damage was not as extensive as first appeared. Suspension and steering was relatively unscathed with the notable exception of the upper offside rear radius arm. Major mechanical components such as engine and ZF transaxle also survived with the only significant damage in that area being the transmission oil cooler brackets (fitted above the transaxle). However, Norman Dewis confirmed in his autobiography that the car had glanced a sand-filled oil drum as it spun towards the MIRA infield. The impact was in the offside cockpit area (the driver’s side) and Dewis’ helmet was damaged when the windscreen pillar made contact with the oil drum and hit it. This contact was further compounded by a series of end-over-end and sideways rolls.

Damage to the body/monocoque structure was extensive and these sections were beyond economical repair. The body structure of the XJ13 is entirely monocoque consisting of two wide sills (containing fuel tank-bags) which run from front to rear wheels. Between the two sills is a section of stressed floor and three bulkhead sections – two at the front and one immediately behind the driver. A further boxed section forms part of the rear bulkhead and serves to connect the sills at the rear . This entire body structure needed renewal – doors and windscreen surround included.

The two front wheels were found to be OK but both rears were broken. Incidentally, this may support the argument that a broken wheel may have been a consequence of the crash and not a cause?

What was changed during the car’s 1972/73 rebuild?

The car remained in its sorry state for more than a year. As the time for the launch of the new SOHC V12 production engine loomed, Lofty England decided the car should be restored as a promotional, rather than a competition, vehicle. I feel the car’s new status both permitted and defined changes that were made to it during its rebuild to fulfil its new role. As a consequence, certain cosmetic changes were made that deviated from Malcolm Sayer’s original design.

Ted Loades of Abbey Panels spotted the crashed XJ13 stored at Jaguar and offered that Abbey Panels would rebuild it for £1,000 - “Lofty” England accepted without hesitation ….

Luckily the original wooden bucks/formers had survived. They had been stored outside at Jaguar’s store at Radfords and had escaped the periodic “clean up” that components stored inside were subjected to.

There are many so-called “eyewitness accounts” of the damage suffered by the car and others claiming to have intimate knowledge of exactly what was damaged/replaced during its rebuild. The following represents the facts that I have been able to establish so far (further changes still under investigation):

• Completely new body/monocoque/doors built by Abbey Panels. Some of the critical dimensions were varied slightly – including the overall length and details of the rear section. A major deviation was the addition of “1970’s” wide wheelarches to enable the fitment of wider tyres/wheels. This deviation from the original design was done to improve “strength and appearance”.
• Further stiffening sections were added at the front of the car as evidenced by an additional row of rivets that appeared across the nose of the rebuilt car.
• A different means of attaching the windscreen to the surround was employed.
• The existing wheels were repaired by Jaguar and Sterling Metals. It has been suggested that new wheels were made by machining the outer section of Concord undercarriage wheels but no documentary evidence to support this has yet surfaced.
• The original light alloy radiator was found to be corroded and so a new one was made by modifying a XJ12 saloon item.
• Twin lightweight Lucas batteries were added to replace the original (which had been found to be not quite up to the job).
• The original seats were retained although retrimmed in a different material to original.
• A different style of gear-lever was used as the original had been “mislaid”.
• The car was painted in a different, lighter, shade of British Racing Green.

So … to answer the question posed earlier – “Why recreate the Jaguar XJ13?” 

Because it doesn’t exist in its original form – completely true to Malcolm Sayer’s vision…

Because there is only one car and that car is in the capable hands of Jaguar Heritage. I am unlikely to be allowed to experience the “zeitgeist” of this car and era by driving it at its limit....

Because the chances of the “original” being raced are nil – my dream is to see a recreation of the 1966 car on a racetrack racing against the cars it was designed to compete against - those from Ferrari and Ford in particular. The “original” will never race – a recreation perhaps could?….

You are invited to join me in my quest to recreate the legendary XJ13 - your contributions, support and interest will be welcomed. The journey continues!

As I write this the XJ13 is still in the US - due to return to the UK at the end of this month. There is a short lull in my own project as I wait for the information needed to take the next step - the production of a 3D scale copy from the digital data as a precursor to the manufacture of the body/monocoque formers.

Rest assured, I shall soon add details of all work that has gone on so far on my recreation of the car as it stood in 1966 - before its rebuild by Jaguar in 1973. Much has been discovered during the process so far - differences between the 1966 original and the 1973 rebuilt car, Jaguar's 3 litre V12 quad-cam thoughts in 1967, another possible cause of the 1971 crash at MIRA, the real reason the XJ13 project was shelved - and much more ....

In the meantime, here are a few pictures of the Jaguar-built 1973 car as it looks today. Click on any image.

I visited the Jaguar Daimler Heritage Trust (JDHT) to attend a signing of a new XJ13 print by Nicholas Watts (see later blog for details). While there, I took the opportunity to crawl all over the XJ13 and take a few photos!

Here is the first instalment (more to follow). This post details the cockpit area of the original XJ13 ...

A happy Jag-enthusiast (XJ13 in front of me and three of the XJ13 design team behind me.....)

My previous post looked at the development of the quad-cam V12 – I now look at how this evolved into the first single-overhead-cam V12 engine.

Much has already been published elsewhere – not least of all by renowned authors Skilleter, Whyte, Porter, Viart/Cognet et al. I hope to add to this body of knowledge with my own small contribution on aspects that may not have been already documented elsewhere.

V12 in 5.3 litre Series 3 E-Type guise.

In the mid-1960s, and coinciding with the British Motor Corporation takeover of Jaguar (to become British Leyland), the instruction was given that Jaguar were to withdraw from racing. This, of course, affected the XJ13 Le Mans project and further development of the racing car and its competition engine was curtailed.

As there was now no need for a competition engine, the emphasis switched to developing the V12 as a production engine. In a production engine, maximum power is less important than low and mid-range torque – allowing Jaguar’s saloons to waft along in effortless silence.

The downdraft inlet port arrangement had been found to be sub-optimal for the Jaguar engine. However, the sheer width of the quad-cam unit would have made the addition of a sidedraft arrangement impractical.

There were two other areas of the quad-cam that could be inappropriate for a production engine – the two-stage chain drive and its use of twin distributors. The two-stage chain drive used in the quad-cam engine proved to be rather noisy and, although acceptable in a competition engine, was inappropriate for a production engine. During the development of the twin-cam, a single engine (No.4) was assembled with a cast-iron block. However, the weight penalty was too great. It is not believed that this cast iron block has survived – although it may have found use as a ship’s anchor …

Comparison of single- and twin-cam chain drive mechanisms.

There were distinct advantages to using a single-cam layout rather than twin-cam:

1. There is a cost saving with the simpler design.
2. There is a significant weight saving (approximately 16lbs per head) if a single chain drive using a single sprocket is used rather than four chains and twelve sprockets – not to mention the smaller head castings and fewer camshafts etc.
3. The overall noise level is reduced.
4. The engine runs more smoothly with only two cams rather than four.
5. The greater width of the “Vee” allows the fitment of a single 12-cylinder distributor and other auxiliaries such as air conditioning compressor.
6. The overall width of the engine is reduced (particularly across the exhaust manifolds) which allows for greater wheel movement and a reduced turning circle.

Comparison of the bulk of a twin-cam vs single-cam arrangement.

Some trials were made with a partial gear-drive to the camshafts but this was unsuccessful and wasn’t adopted.

Changes were also made to the cylinder block. Wheras the twin-cam engine had a solid top deck, the later single-cam engine had an open deck. As well as weight savings, the latter design meant the block could be die cast to save money – an important consideration at this time in Jaguar’s history. Also, wheras the twin-cam engine sump face coincided with the crankshaft centreline, the single-cam engine’s sump face was much lower. 

Final cylinder block design showing the “open” deck and receptacles for cuff type push-fit liners. This picture is actually of a block that was used to create a coffee-table!

Perhaps surprisingly, it was found that the assembled non-decked cylinder block, with its associated webbing, was more rigid than the solid deck design of the twin-cam block.

Single-cam cylinder block from beneath showing main bearings and studs.

Just before the end of 1969, it seems that exhaust emissions were compared between the most highly-developed twin-cam competition engine (No.2) and the new single-cam production prototypes. It may have been found that the competition engine was more efficient in emission terms but other considerations will have weighted the decision towards a single-cam arrangement.

A number of single-cam prototypes were assembled and trialled between 1971 and 1977 – development continuing long after the introduction of the new single-cam engine in the Series 3 E-Type of 1971. As well as being developed on the test bed, these prototype engines were fitted to saloon cars for road trials.

Details of a selection of these prototype V12 single-cam engines are as follows:

Other projects – at least three with a 4-valve twin-cam arrangement – were also trialled between 1974 and 1978. The findings and data from these trials will have been fed into the ongoing V12 project. These engines were “slant six” twin-cam engines of between 3.6 and 3.8 litres capacity.

The following chart gives a comparison of performance of the two engines (5 litre twin-cam competition and 5.3 litre single-cam production).

Power curves of single and twin-cam engines.

In the above analysis, each engine used a Lucas mechanical fuel injection system with individual intakes and open exhausts – must have made quite an impressive noise at peak revs …

The single cam engine gave a much better performance up to 5000 rpm where its power reached a healthy 360bhp . The twin-cam competition engine, however, really came into its own above 5000 rpm and achieved over 500bhp @ 7,500rpm.

It is interesting to note that while looking for cost-cutting measures, Jaguar decided to inset the valves by 0.050” in the flat single-cam cylinder head. They could save money by doing this because there was then a higher permissible speed for the cutter used to dress the heads. This meant they could speed up this part of the process. Their static air tests indicated this wouldn’t make any difference to power. However, this cost-saving measure did reduce power in practice as can be seen from the following chart.

Curves showing effect of valve-seat insert depth.

Jaguar looked at various ways of fuelling their new engine – ranging from Lucas mechanical injection as used on the competition engine to carburettors. The first production engine, as fitted to the Series 3 E-Type used carburettors although this quickly gave way to a fully-electronic system to meet the demands of emission control and performance. The system used on the first single-cam injected engines was a fully-electronic fuel-injection system as jointly developed by Lucas and Bosch. The fuelling system continued to evolve throughout the V12’s history.

Single-cam engine showing carburettors (left) and petrol injection (right).

Although originally conceived as a competition engine to keep Jaguar at the forefront of sportscar racing, the possibility of eventually fitting the engine into production cars was always at the back of Lyons’ mind. However, up until the mid 1960s, the emphasis was primarily on competition and racing. This emphasis changed in the mid 1960s towards a “production engine” and the result was the long-lived single-overhead-cam V12. Although many compromises were made along the way, the first production V12 became a commercial success and went on to power a range of Jaguar saloons and sports cars.

I am proud to own an engine that was developed at a time when racing was its main reason for existence. I hope to sympathetically restore this engine and place it in an appropriate home – a copy of the XJ13 Le Mans racer as it was in the mid-1960s – perhaps even fulfilling its competition intentions.

Watch this blog!

Last month I made a post looking at the origins of the V12 – this month I look at the development of the V12 in a little more detail.

Before the V12, Jaguar’s racing and practically all road cars were powered by the powerful and renowned XK straight-six double overhead-cam unit. This engine had its origins in pencilled sketches drawn during the London blitz by Sir William Lyons and his engine designers; William Heynes (Chief Engineer), Walter Hassan and Claude Baily. These sketches and original designs were followed by working prototypes as early as 1943. The first 3,442cc production unit saw the light of day in the beautiful XK120 of 1947. The same basic engine continued production into the 1990s.

1947/1948 Jaguar XK120.

3,442cc Jaguar XK engine.

XK engine cross-section.

This engine went on to power Jaguar to a number of famous Le Mans wins. However, as early as the mid 1950s, the pace of international racing engine development led Jaguar to believe they needed to develop a successor to the XK engine to keep them at the forefront of racing. The Le Mans Sports Car Regulations at the time dictated the maximum capacity of the new engine – up to 5 litres. The Jaguar engineers agreed that the maximum power and tuning potential could be achieved with either a 8-cylinder or 12-cylinder “Vee” formation. The current XK engine had a relatively long stroke and the ability to achieve greater power by running at higher revs was compromised by this design. The XK's cylinder bore of 83mm and stroke of l06mm resulted in a piston speed of 3,820 ft./minute at 5500 r.p.m. – much faster and the engine integrity could not be guaranteed. It was decided that the future engine would have a reduced stroke of 70mm which would allow the engines to run safely up to 8,500rpm.

In around 1965, the project became reality when a number of V12 cylinder blocks and associated components were commissioned. These blocks were used to build up two types of engine – one with internal modifications made to allow a specially-modified crankshaft, lacking two “throws”, so the unit could function as a V8; the second was a full V12.

It is believed that only one of the original “V8” engines has survived. Although not salveageable and not able to be made to run either as a V8 or V12, it survives as a display model. The following picture shows this engine as it appeared in the collection of the late Jaguar collector Walter Hill in the 1980s:

V12 prototype block internally modified to run as a V8.

My previous post on the V12 made reference to the fact that, of the originally-planned eight V12 engines, only four are known to survive today. Two (Nos.1 & 7) remain with the Jaguar XJ13 Le Mans prototype, one (No.2) has survived as a complete engine and is in the process of a full restoration prior to being placed in an authentic recreation of the original 1966 XJ13. The fourth V12 (No.8) was placed in a rather inaccurate XJ13 copy – made by the well-known and talented car builder Bryan Wingfield and sold to the collector Walter Hill.

In Wingfield’s own words (as reported in “Supercar Classic” magazine) – “I got a call from somebody I knew at Jaguar who told me that there were a couple of old prototype engines lying around which were of no use to anybody else, and asked whether I was interested … I had to buy those V12s through another engineering company.”

The Wingfield copy survives today as a running car – albeit with “Ford GT40-inspired” chassis and an approximation of the XJ13 body shape. The engine itself was bought as “a box of bits” and was made up from assorted original and new parts. The most desirable feature of this engine, the only heads with the ultimate development of intake angle (41 degrees), were removed from the “Wingfield” No.8 engine some time before its sale and fitted to the No.2 engine by Jaguar in 1969 and remain with the No.2 engine to this day.

V12 prototype twin-cam engine - stages of inlet port angle development. Greatest power was developed with a 41 degree inlet angle.

V12 prototype twin-cam engine – original inlet port angle (left) and final angle (right).

It was known that a V8 configuration needs a two-plane crankshaft with wide outer crankshaft balance weights to run smoothly. A V8 firing sequence is also not as efficient as a V12 if carburettors are used. In comparison, the V12 engine has equal firing impulses along each bank and can be treated as two sets of 6-cylinder engines as far as carburation is concerned. The V12 engine is inherently smoother than a V8. As well as these technical reasons for favouring a V12 over a V8, the USA car market was very important to Jaguar. It was felt that a V12 would have greater appeal than a V8 in this market.

The first V12 prototype was assembled in 1964. The prototype engine main features were:

• Twin overhead cam per bank
• 87mm bore x 70mm stroke
• 4,991cc capacity
• LM8 (aluminium) sand cast cylinder block
• Sump face on crankshaft centreline
• Top deck with flanged split rim cast iron liners
• Seven main bearings of 3.0” diameter
• Side-by-side connecting rods offset 0.75”
• 2.187” diameter crank pins
• Forged steel crankshaft with eight balance weights
• Crankshaft lubrication end-to-end feed fed from grooves in the main bearings
• Crankpins using sludge trap system used on the XK 6-cylinder engine and transverse feed holes
• EN 4A nitrided crankshaft

The following picture shows the second engine that was assembled in 1964 – as it is today.

V12 prototype twin-cam engine – with Peter Wilson (Jaguar Competitions Department 1961-1966) – complete with ultimate development of cylinder heads.

The prototype V12 cylinder head design was very similar to the tried-and-tested XK 6-cylinder head design but with a number of important differences.

The depth of the new combustion chamber was shallower (1.03” versus the XK’s 1.30”) and the included valve angle was more narrow (60° versus 70°). The combination of shallow combustion chamber and narrower angle was theoretically more efficient.

The following comparisons were made during development:

Competition and production versions of the twin-cam engine were developed at the same time. They were all basically similar except for things such as valve and port sizes and camshafts. Ideally, the prototype engine would have employed the use of transverse inlet ports which became the norm for equivalent competition engines being built by Ferrari and B.R.M. This was found by Jaguar to be a more efficient layout for their engines but it would have been impossible to fit a V12 engine with transverse ports such as those on the XK 6-cylinder engine, with an adequate induction tract length, within the confines of an engine bay – even that of the Mk10! While the competition version was being developed, Lyons and Hassan kept in mind the need to eventually fit a version of the engine in a production car.

During development, Jaguar found that the two stage chain drive was not completely reliable and the noise level was deemed unacceptable in a sophisticated saloon car. For this reason, a partial gear-drive was proposed for the competition engine camshafts as in the following diagram:

Camshaft drive (with gears) proposed for the competition engine.

However, this arrangement was never fully developed. A single engine was completed to this specification and was run on the test-bed. However, it remained in storage after the Le Mans project came to an end and was not fitted to the XJ13 car until 1978 when a missed gear necessitated an engine change – long after the project had ceased and the rebuilt XJ13 was only used for demos etc. For all its development life, the XJ13 ran with duplex chain drive to its camshafts.

The original engines were fitted with twin distributors which were found to be troublesome. One incorporated two sets of contact breakers plus the centrifugal and vacuum advance mechanisms for both; the other was used simply to distribute the HT current. At high engine speeds difficulty was experienced in matching the timing of the two sets of contacts and the variations were deemed unacceptable.

The following picture shows the original twin distributors as still fitted to the surviving engine number 2:

Twin distributors fitted to surviving V12 prototype No.2.

As may be apparent from the picture, it would have been difficult to fit a single 12-cylinder distributor in the “Vee” and so this twin-distributor arrangement continued throughout development. Around 1973, at about the time the crashed XJ13 was rebuilt by Jaguar, they were able to modify and fit a single 12-cylinder distributor and also updated the ignition system to OPUS (Oscillating Pick-Up System). A twelve-cylinder engine running at 6000 rev/min requires a spark rate of 600 sparks/second which is well above the capability of a conventional make and break “points” system (400 sparks/second). OPUS uses an electro-magnetic pick-up and electronic solid-state switching, mechanical delays are eliminated. The prototype engines were subjected to extensive testing – not only in cars (including the XJ13) but also on the test-bed. My own engine, No.2, was also fitted to two Mk10 Jaguars. These big and heavy cars, one white and one sable, were used for road trials as the original XJ13 may have been rather too conspicuous! There are many stories surrounding these two cars including a road test by “Wilkes” of Motorsport magazine who was allowed a test drive on the understanding he never opened the bonnet to see what was inside! Retired ex-Jaguar employees also tell stories of how the cars were used to surprise and embarrass the Aston Martins being tested on the M1 motorway around Newport Pagnell …

The following picture shows this engine fitted with six carburettors for these road tests. Close examination reveals its origins as the dry sump originally fitted in 1964 (modified to wet sump for fitment in the Mk10s).

Archive photo of No.2 V12 prototype – as fitted to Mk10s.

Towards the end of the V12 project the emphasis switched from racing to powering a production saloon. This eventually led, via prototype single-overhead cam V12 engines of 6.4 and 5.3 litre capacity, to the final 6.0 litre HE engine of the mid to late 1990s.

Developments from the quad-cam racing engine to the final single overhead cam engine will be covered in a future post.

To be continued ….

Original 1966 XJ13 Windscreen

Whilst sourcing parts for the rebuild of the 1966 car, I came across a reference to the use of an "original XJ13 windscreen" which prompted me to contact Pilkingtons on the off-chance the original windscreen patterns may still be available. The reference to the use of the original windscreen formers was found in a XJ13 brochure produced by Jim Marland (former owner of Proteus Cars) in the 1990s. I now have the information I need to ensure my recreation will follow the lines of the original windscreen exactly

ADDITIONAL NOTE (9th July 2010)

Pilkingtons have now confirmed that the windscreens commissioned by Proteus Cars for their replicas in 1990/91 differed slightly from the original. This was because windscreens made using the original metal former did not fit the replica produced by Proteus Cars.

Pilkingtons may have not made any windscreens using the original 1966 metal former within the last 38 years. It is likely the last windscreen was made in 1972/73 for Jaguar's rebuilt car. Subsequent claims by various replica builders that they used "the original windscreen moulds" are likely to be untrue.

When the "original" XJ13 was rebuilt in 1972/73 a new Triplex screen was commissioned by Jaguar. The XJ13 Log Book states about the rebuild in 1972/73, "... new formers made for windscreen & doors. Perspex used although laminated Triplex ultimately to be fitted ...".

The newly-manufactured accurate windscreen can now be laser-scanned and digitised. This information can then be added to my 3D digital CAD/CAM millimetre-perfect 1966 XJ13 representation (more information about this approach to follow).

Long-suffering wife holding the wooden "fitment gauge".

It was interesting to note that the last transaction Pilkingtons have for the use of the original windscreen formers was in 1991 - with Jim Marland of Proteus. I have come across a number of other references to the use of the "original windscreen formers" by various replica builders since then - it does question the accuracy of their statements.

Pilkingtons (who absorbed Triplex in the 1960s) are a major multinational supplier of glass - in all its forms. Of interest to builders and restorers of classic cars and one-off specials, is their small manufacturing facility on the Isle of Sheppey in Kent, UK.

Classic Windscreen Manufacture in the UK

Pilkington Automotive has a windscreen factory in the UK designated for short run production of classic and special parts. It is located in Queenborough on the Isle of Sheppey in Kent.

General view of production area

The range consists of over 2000 parts including AC, Mercedes, Aston Martin, Jaguar and Lotus - to name a few.

The manufacturing facility employs 14 people who have the specialist skills required to enable small batch production runs of laminated glass to take place.

Windscreens for Classics

The Queenborough factory has made classic windscreens for the aftermarket since the late 1950s, and still retains the vast majority of the tooling produced "in-house".

Many owners of classic cars have turned to the Queenborough facility as a "last resort" when searching for that rare windscreen. They can work from CAD data but if the tooling is not available then it is sometimes possible to adapt, rebuild, or produce new tooling if required.

Checking gauge/jig for Mosler.

It seems that no volume is too small for Pilkingtons Automotive - knowing that the original XJ13 formers are safely maintained at their factory, I only requested a single windscreen - safe in the knowledge that I can order a replacement and have it delivered within days if needed.

They produce single windscreens against samples or provided fixtures, also drawings if the part is flat (see following paper templates previously provided by custoners):

Customer-supplied paper templates for flat screens.

Each part is individually costed so as to accurately match the customer's requirements in shape, colour, thickness etc.

Pilkingtons Automotive may be contacted via their website www.pilkington.com

Pilkingtons Automotive brochure.

Production Process

The process starts with the customer requirement. This may be satisfied from Pilkington's existing comprehensive stock of original jigs and formers or by customer-supplied drawings/templates. While there, I saw customer-supplied templates made from paper, wood, plastic, computer-cut resin etc.

GRP/Perspex racecar prototype customer-supplied template.

Rolls-Royce customer-supplied wooden templates.

Customer-supplied template.

Flat glass sheets are then cut by hand using flat wooden templates. Each laminated screen consists of two flat sheets which sandwich a vinyl laminate. The vinyl laminate can contain heated elements if required. Care is taken to ensure the correct quality/thickness of glass is used and also that the edges of the glass are precise right-angles. The "glass sandwich" is assembled by hand and then subjected to great pressure/heat in a purpose-designed autoclave. This process ensures that, not only are the layers permanently bonded together, but all air is excluded. If required, black/shaded edgings are added. Each windscreen is then given its appropriate "BS" safety mark. In the case of my windscreen care was taken to ensure that the location and contents of this mark was exactly as original. If the finished car is ever raced, FIA scrutineers will refer to these markings.

Production area stock of flat wooden glass templates.

"BS" safety markings being applied to the flat glass "sandwich" for the XJ13 windscreen - the production operator was rather camera-shy!

Each windscreen has a steel former made for it. These are all manufactured on site by hand by Pilkingtons. These are precise pieces of engineering and most are "hinged" and counter-balanced to allow them to guide the glass gently into its final shape as the heated glass softens and gently "falls" into the former. Pilkington has extensive stocks of these metal formers - not only at Queenborough but also at their other production sites. The original steel former for the XJ13 windscreen was stored at Pilkington's Kings Norton plant before being transported to Queenborough.

XJ13 glass "sandwich" being placed on top of original metal former. The whole assembly sits in a "trolley" ready for its journey through a series of heaters.

Factory store of metal formers - chances are, the one of these will be for your rare classic.

Various formers for E-Type Jaguars.

Early 1950s stock of formers - it was interesting to see how the width and curvature has changed over the years. Early windscreens were relatively flat - modern screens tend to be much larger with complex curves.

At the same time these metal formers are made, a complementary wooden "fitment jig" is made. This wooden jig is used to check the accuracy of the finished windscreen. Again, these are all made by hand at Pilkingtons by skilled craftsmen.

Jaguar XJ13 wooden fitment gauge.

Ferrari Dino wooden fitment gauge (Ford Capri behind it).

Batch of completed MGB windscreens showing how the fitment gauge is used.

Peter Swann (Factory Manager, Pilkingtons Automotive Queenborough) searching for a fitment gauge - note the (very) important fire extinguisher!.

Meanwhile, my XJ13 windscreen is continuing its journey through the furnace. After a pre-heating stage, the windscreen is subjected to gradually increasing temperatures provided by an array of individually-controlled burners. The operator monitors temperatures in the furnace and controls the burners to ensure an accurate windscreen emerges. Just before the glass reaches 700 degrees C, inspection windows in the furnace allow the operator to see the glass begin to "fall" into the metal former until it takes up the precise shape required. This is a very skilled manual operation and relies on the operator's experience and judgement. Too much heat/time and the windscreen will "sag" and become concave, too little and it won't take up the desired shape. Once it begins to bend, it is all over within minutes. Except for four small contact areas, nothing must come into contact with the glass surface while it takes up its final shape. These four small contact areas between to former and the glass are dressed with small pieces of a heatproof paper.

Jaguar XJ13 windscreen passing through furnace.

Tiny windscreens can be made using suitably-sized metal formers ......

Jaguar XJ13 windscreen manufacture personally supervised by the Factory manager, Peter Swann!

The finished windscreen emerged from the furnace and, once it had cooled, we were able to check it using the wooden fitment jig. A small difference was eventually traced to a difference between the fitment gauge and the original steel former. After suitable adjustments, I am now the proud owner of an accurate Jaguar XJ13 windscreen - completely faithful to the original.

The windscreen will be laser-scanned and its data added to the digital data currently being assembled for a an accurate recreation of the 1966 car.

I wish to record my sincere thanks to Pilkingtons Automotive, Peter Swann and his staff, for their assistance and for providing an insight into this aspect of car manufacture. If you are looking for a windscreen for your classic, special or prototype I recommend making contact with Pilkingtons Automotive - it may be that they already have the necessary formers/templates for your particular car. In these days of mass-production it is so refreshing to find craftsmen, employing these tried and tested techniques.

To be continued ......

Lucas Fuel Injection

Fuel supply to the original 1966 XJ13 was managed by Lucas Mechanical Fuel Injection.

This system was retained by Jaguar when the car was rebuilt in 1972/73 and remains with it today. The heart of the system is the Lucas metering unit which sits in the "V" of the engine and distributes fuel to each of the 12 cylinders.

The following picture shows the unit in-situ in the car today:

Lucas Fuel Injection unit fitted to the "original" XJ13

The unit is belt-driven at half engine speed using a cog provided at the end of the distributor drive. The following picture shows the cog and mounting points on my engine (prototype engine No2) - just crying out to have a metering unit fitted!

Mounting point for Lucas Fuel Injection metering unit

This type of fuel system was "state of the art" in the 1960s and was fitted to many Ferrari and Maserati racing engines of the time. Finding an original unit proved to be very difficult. Although I actually succeeded in tracking down an original unit which the owner claimed had been removed from the original XJ13 during its rebuild in 1972, it turned out to be so badly damaged and corroded that renovation would not have been possible.

These units are manufactured to tolerances of less than one tenth of a thou and are absolutely critical to the efficient running of the engine. Bearing this in mind, I decided to commission a new unit - built to the original specification. I was fortunate enough to be able to make contact with one of the few engineers capable of carrying out such a task and I am now the proud owner of a brand new, original specification metering unit. It was pleasing to find that the skills to make the units are still available in the Midlands - not too far away from Coventry. These units are truly "works of art" and I look forward to the day when it can take pride of place atop my V12 prototype engine.

Newly-manufactured Lucas Fuel Injection Metering Unit.

Newly-manufactured Lucas Fuel Injection Metering Unit.

The Lucas petrol injection system has been outstandingly successful on high performance cars, particularly in the international racing field. During 1966-67 the first three places in almost every Grand Prix event were held by cars equipped with a Lucas petrol injection system.

1969 Lucas Ad.

A conventional carburettor is not required in the petrol injection system. Instead fuel is injected into each of the 12 air-intake ports by means of this high-pressure metering device.

Some of the more important advantages to be obtained from the use of petrol injection are:

• Reduced Fuel Consumption - A more economic use of fuel, because the quantity injected into the cylinders is closely regulated to suit the engine operating conditions.
• Smoother Running at Low Engine Speeds, and Better Acceleration - Engines fitted with fuel injection equipment accelerate quicker and have greater flexibility, particularly at low engine speeds.
• Increased Performance - A complicated manifold is not required, so that the air intake is greater than normal. This ensures improved volumetric efficiency and hence increased power.
• Cleaner Exhaust Emission - As there is almost complete combustion in the cylinders, the amount of unburnt hydrocarbons and carbon-monoxide is reduced. The result is ‘cleaner’ exhaust emission.

Original Lucas Ad.

The amount of fuel in each injection, and the frequency of the injections, is controlled by the metering distributor and mixture control unit. The mixture control unit regulates the amount of fuel in each injection, in accordance with the requirements of the engine. The function of the metering distributor is to inject fuel into each individual inlet by a system of shuttle-metering. The two component parts - the metering distributor and the mixture control unit - are a “matched” pair.

The metering distributor consists essentially of two parts; the rotor and the sleeve. The rotor has two radial ports, which lead to a centre bore containing a shuttle - which is movable between two stops (one fixed and the other adjustable). The sleeve has fuel inlet and outlet ports. The rotor fits inside the sleeve and is connected to, and driven by, the engine.

A critical component of the metering unit is the "fuel cam" - a lever which is connects the accelerator linkage to the metering unit and controls fuel supply to the engine as required. The following drawing shows the design of fuel cam as originally fitted to the XJ13.

Drawing used to manufacture original XJ13 fuel cam. Drawing produced by George Buck of Jaguar in 1966. © Jaguar Heritage.

The profile of this cam is absolutely critical to efficient running of the engine and a number of different profiles were tried out at different times during engine test-bed development.

The following extracts from a report by George Buck in April 1966 confirm the final fuel cam specification used when the engine was first installed in the XJ13:

Extract from George Buck April 1966 report. © Jaguar Heritage.

Extract from George Buck April 1966 report. © Jaguar Heritage.

Extract from George Buck April 1966 report. © Jaguar Heritage.

To be continued ....

Part One - Origins

For 25 years, between 1971 and 1996, Jaguar’s smooth and refined V12 power unit powered the Series 3 E-Type as well as a range of luxury saloons. Right from the outset the engine was designed with enormous tuning potential reserves and, in racing form, powered cars such as the Le Mans winning TWR prototype racers. Its tuning potential was taken to extremes in the world of offshore powerboat racing as well as drag racing.

Of course, the production V12 engine was not a new idea – the first production use of a V12 was as early as 1915 in Packard’s “Twin Six”.

Other manufacturers such as Fiat (7 litre V12) and Daimler (“Double Six) followed. V12-equipped cars soon proliferated and offerings were available in America from Auburn, Cadillac, Lincoln, Packard and Pierce-Arrow. The Germans followed suit with the Horch and Maybach. In 1930 Tatra of Czechoslovakia offered a 6 litre side-valve V12.

One thing all these cars shared was the association with “refinement” and “luxury” that a V12 configuration offers. This reputation was further enhanced by Hispano-Suiza’s use of a 11.1 litre V12 and Rolls-Royce’s 7.3 litre Phantom III. Early engines tended to have push-rod actuated valves although, just before hostilities commenced in 1939, W.O. Bentley designed a high-revving 4.4 litre for Lagonda with valve-gear very similar to the later Jaguar’s. Since 1945, the V12 became associated with quality Ferraris, Lamborghinis and Maseratis – especially in racing applications.

Jaguar’s V12 does have the distinction of being the first British manufacturer to emerge from WW2 with the first British V12. But why did Jaguar choose the V12 configuration? According to Walter Hassan, OBE and Harry Mundy, both credited with Jaguar’s V12, said the V12 layout gives perfect balance which allows high-speed running and the power potential which accompanies this.

Jaguar’s Walter Hassan (Chief Engineer – left) and Harry Mundy (right)

At the time, this was an important step for Jaguar. They invested over £3 million in tooling for mainstream manufacture of their engine – without an “economy” model to fall back on if the world decided that large capacity V12 engines were not the way forward. It is no coincidence that, early on in the V12 prototype project, alternate configurations such as a V8, slant-6 and straight-4 designs were trialled.

Jaguar had first considered a V12 as early as the 1940s. Claude Baily realised that a replacement for the 6-cylinder XK engine would eventually be needed – particularly if Jaguar were to continue their racing successes in the face of fierce competition from Ferrari and Ford.

In 1964, a first formal “Instruction To Proceed” was issued giving the go-ahead to build a number of V12 prototype engines. A second instruction was given in April of 1965 by Claude Baily for this engine to be installed in the planned prototype Le Mans racecar – the XJ13. In June of 1965 a further “Instruction To Proceed” was issued for construction of the XJ13 itself. The plan was to develop and install this engine in the XJ13 with the aim of repeating their successes at Le Mans in the 1950s. The emphasis of this V12 engine project was very much on racing from the outset – with the possibility of a production engine arising from this experience.

“Instruction To Proceed” © Jaguar Heritage

The first of these engines (engine “number one”) was assembled in July 1964. In common with all previous Jaguar projects, the prototype V12 project was given an internal code. The code for this project was “XJ6” – not to be confused with the later car of the same name!

XJ6 Project - Engine Log © Jaguar Heritage

Conducted in great secrecy, Jaguar’s Competitions Department and Engine Development Department kept meticulous records for each of the engines built, developed and tested. Thanks largely to the efforts of Jaguar Heritage, many of these records have been preserved and safely archived. The detailed log books for all but one of these “XJ6” engines survive (although the “missing” log book may, in fact, be for an engine that never existed as a complete engine). The first prototype V12 was assembled in July of 1964 (engine number one).

XJ6 Project - Engine Log © Jaguar Heritage

In total, it is believed that six complete engines were assembled as part of the XJ6 project. One of the six was assembled using a cast iron block (engine number four – not believed to have survived testing) although the remainder were cast alloy. It was common practice within Jaguar in the 1960s to scrap engines and components when no longer needed and, of this original six, it is believed that only four survive today. Two of these engines (numbers one and seven) remained with the XJ13, one had a privileged existence following extended development (number two) and one was built up from a collection of new and used spare parts long after the project had ceased (number eight).

All these engines were initially assembled with dry sumps and duplex chain drive to the camshafts. The only exception was engine number one that had a gear-driven camshaft arrangement fitted after the XJ13 development had pretty much ceased – this modified engine was fitted to the XJ13 as late as 1978 by which time the car was only wheeled out for demonstration runs etc. For all of its active development life, the XJ13 was powered by engines with duplex chain drive.

The engine blocks themselves were cast by the West Yorkshire Foundry. The foundry on Clarence Road Leeds started production in the 1930's; its closure was announced in September 2003.

West Yorkshire Foundry

The blocks were machined by Coventry Climax and returned to Jaguar for assembly. The Coventry Climax company has its roots in 1903. In 1950 Walter Hassan joined them and designed the FWA, a feather weight engine for automobiles. The first Coventry Climax racing engine appeared at the 1954 Le Mans 24 Hours in the back of a Kieft. The engine became popular in sportscar racing and it quickly became the engine to have in F2. Coventry Climax was purchased by Jaguar only one year before the quad-cam V12 project – bringing Walter Hassan to Jaguar where his talents were further exploited.

The engine logs give information on exactly how each engine was assembled as well as their detailed development history on both the test bed and when fitted to cars. The logs also refer to a number of technical reports – many of which survive in the Jaguar Heritage archive. Practically every engine component was individually coded and it is possible to trace their movements from one engine to another during development.

To be continued …..

The XJ13, as originally envisaged by Malcolm Sayer and built in Jaguar's Competitions Department, is different in a number of respects from the rebuilt car which now graces Jaguar Heritage's collection.

Chief amongst these differences are the different wheels and treatment of the wheelarches.

The following animated image attempts to show how Sayer's classically elegant and timeless lines are emphasised in the original, 1966, car:

1966 XJ13 superimposed on the car as it is today

It may be argued that, although the present wheelarches and wheels give the car a more contemporary "aggressive" stance, perhaps something of the understated elegance of Sayer's design has been lost? One thing it does seem to have lost is the appearance of being "on the move" even when it is standing still. What do you think?

Whatever your views, the car was united with its first prototype engine in 1966 and (according to Peter Wilson) was originally shod with "Lightweight E-Type" wheels similar to these:

"Lightweight E-Type Alloy Wheel"

The following original drawing (shown courtesy of the Jaguar Daimler Heritage Trust) show how Sayer intended the car to look - complete with his treatment of the wheelarches.

Original XJ13 - © Jaguar Daimler Heritage Trust

In 1967 (as recorded in the XJ13 Log Book) extensive modifications were carried out to the body to accept different tyres. Some of these "extensive modifications" involved chopping out and reshaping the rear wheel arches (the fronts seem to have been largely untouched) and the fitment of the style of wheels as seen on the car today. Is it possible this was chosen as an easier option rather than modify the driveshafts/suspension etc? It seems perfectly possible to have fitted wider tyres and remain faithful to Sayer's original design?

The timing of the change fits in with extensive testing at Silverstone where both drivers reported issues with rear wheel grip/steering/feel. Was the fitment of wider tyres a knee-jerk reaction to this? Detailed investigations of the car after the Silverstone tests revealed that not only was the wrong rubber compound supplied by Dunlop, but an imminent driveshaft/bearing failure will have resulted in uncontrolled camber changes of the rear wheels during testing.

During the car's rebuild in 1972/73 the front wheelarches were widened to suit the rears and "eyebrows" were added all round. The reason for the "eyebrows" was given as "for cosmetic reasons" and for "stiffness".

There are many other differences between the 1966 car and the car we see today - some quite subtle and others much more obvious. As this project proceeds I shall continue to attempt to unearth the 1966 car ...

I was privileged to be visited by Peter Wilson (ex Jaguar Competitions Department) who confirmed the identity of my prototype quad-cam V12 as being the second engine to have been built as part of Jaguar's quest to return to Le Mans with the XJ13.

Peter worked in the Competitions Department for five years up to 1966 and had hands-on involvement in the construction of the XJ13. Although a number of people have since claimed involvement in the project, many did not even set foot in the Competitions Department! - Peter is one of the few surviving members who can claim first-hand participation in the building of the XJ13 Le Mans prototype racer.

Since leaving Jaguar, he has worked in a number of prominent and senior positions in the automotive industry including time spent Brico Engineering, Cummins Diesel Engines and British Leyland. Since his retirement in 1999 he has written the definitive work on the Competitions Department between 1961 and 1966 including not only the XJ13, but a significant era in the racing and development of the E-Type. I can heartily recommend Peter's book "Cat Out of the Bag" which is available from Paul Skilleter books at http://www.paulskilleterbooks.co.uk/

Peter Wilson - Jaguar Competitions Department 1961-1966 with the second prototype quad-cam V12 engine

Peter is an engaging character with an absolute wealth of information on Jaguar. His straight-forward and no-nonsense account of people, places and the cars kept me absolutely enthralled during his visit. He is a very likeable person with a truly remarkable memory for the detail of past events.

I learnt a lot from Peter about my own engine - in particular:

• It is without doubt the second engine assembled by Jaguar as part of their "XJ6" (quad-cam Le Mans V12 engine) project
• It possesses the ultimate development of the quad-cam head (heads nos 18 & 19)
• The engine was fitted to two Mk10 (XJ5 Project) Cars for continued testing - I guess the XJ13 itself would have attracted too much attention! The engine was removed from the car in 1969 and then stored in the Experimental Department after a short time on the test-bed.
• The engine appears to have been untouched since being displayed at the Coventry Herbert Art Gallery & Museum in the early 1970s (engine still in the ownership of Jaguar).
• It is likely the engine was transferred to Jaguar (Germany) for display from where it was eventually sold to a member of the general public around 1980 (the engine was subsequently displayed at the Essen Motorshow in 1998 - see HERE
• The engine today remains in the same condition as when it was removed from the development test-bed in 1969 (albeit with an external cleanup for display! - the final tests carried out on the engine were to measure exhaust emissions - probably as a comparison with the later SOHC "Heron" V12 project)
• Although the engine has a wet sump (fitted when installed in the Mk10 project cars), it is a converted original dry sump.
• Although fitted with 6 x SU carburettors when installed in the Mk10 cars, the engine was initially assembled with Lucas mechanical fuel injection as the XJ13.

Peter is now engaged on writing an account of the XJ13 and we look forward to this latest book. There is so much myth and misinformation about the XJ13 that it will be very valuable to have an account written by someone who was "really there" and at the heart of the XJ13 project. For example, he was able to confirm that the XJ13 cam drive was always by means of duplex chain and certain changes made to the original car during its post-crash rebuild in 1972/73.

For now, Peter's last book, "Cat Out of the Bag" contains a whole chapter on the XJ13 with much previously-unpublished material.

In the words of Norman Dewis, Jaguar Test Driver, in his book "Developing the Legend" ... "It was all the fault of the Series 3 E-Type and the new Hassan/Baily 'flat-head' production V12. The idea emerged that the new Jaguar V12 engine in the Series 3 E-Type should be launched to the press at Geneva in March 1971 amid the sight and sound of a previously unrevealed, mid-engined V12 Le Mans car emerging into sight from behind the trees. This involved getting the XJ13 out of hibernation, and as a backup to the press launch, a film would be made for wider distribution. So it was that on 20 January 1971 a film crew from London met up with the XJ13 and Norman at MIRA. After being under wraps for over two years, the car had needed a complete check-over and, as the wheels it was on had done most of the development work, they were substituted by new wheels and tyres which had remained in the stores.

All went well at first, with a good number of laps put in at modest speeds for filming. 'Then to conclude', Norman relates, 'I was asked if I could do four fast laps. I did three, and they were quite quick, although not as quick as I had gone in testing. Then on the third lap I came onto the banking, which was the one opposite the tunnel banking where the film crew were, at about 135, and gave it full throttle to hold it in as usual. About two thirds of the way round the banking, the car lurched to the right and almost instantly went into the safety fence ..."

... the car somersaulted off the track into the muddy field ... tyre tracks showed how the car had almost left the banked section ... then spun down the banking to end up in the field ...

The XJ13 Log Book simply states "20.1.71 Written off" at the top of the entry ..

The following quoted text is © Jaguar Daimler Heritage Trust and should not be copied without their permission.

20.1.71
Written Off. Subsequently stripped by G Gardner to assess total damage.
Car rebuilt (commenced March 1972) completed June 1973.
Body panels - front & rear also doors by Abbey Panels at their works. Formers found intact at Radfords sent over to Bayton Road, also main chassis platform.
Damage not really extensive as regards suspension, steering etc, only one (upper) radius rod at rear o/s & transmission cooler brackets.
Engine stripped and rebuilt up to best show standards. Headlamps supplied FOC by Lucas. Tanks, oil and fuel overhauled by Marstons at cost of £55. Water rad - light alloy - corroded & u/s. XJ12 modified to suit. Two rear wheels u/s, repaied by ourselves & Sterling Metals. Tyres supplied FOC by Dunlops. Brakes OK. Steering column and rack OK. New formers made for windscreen & doors. Perspex used although laminated Triplex ultimately to be fitted to screen.
Flairs added to wheel arches to improve strength and appearance.
Twin lightweight batteries (Lucas) used.
Cooling fan (XJ12 type) fitted.
Pipework cleaned up to improve appearance.
Throttle mechanism reworked.
Seats retrimmed in black cord.
Body painted by Service Dept in new BRG
Dunlop Trackmark used as tread step protection.
New gear lever fitted as original was mislaid?

Rebuilt by G Mason & P Dodd

Car shown to Motor, Autocar, BBC etc & subject to write up in all journals.

Taken to Silverstone on July 13th 1973 for show purposes & demonstration laps (British Grand Prix) also to Shelsey Walsh for Jaguar Owner Drivers Club Rally (Aug 18th & 19th 1973) and XK Register Rally @ Woburn Sun Sept 2nd 1973.

Took it over to BBC Pebble Mill for television programme Thurs Sept 20th 1973.

Weights after rebuild
Less petrol. Plus oil & water

Front LH Wheel - 456lbs
Front RH Wheel - 450lbs
Front axle complete - 926lbs

Rear LH Wheel - 716 lbs
Rear RH Wheel - 640 lbs
Rear axle complete - 1364lbs

Total car weight - 2290lbs

--- END OF XJ13 LOG BOOK ---

As "secret" testing of the XJ13 continued, the car was taken to the Silverstone race circuit for two days in August of 1967 ...

The following quoted text is © Jaguar Daimler Heritage Trust and should not be copied without their permission.

Ninth test August 15th & 16th 1967 - Silverstone

222 miles
Sustained testing at Silverstone over 222 miles and subject to special report by M Kimberley (see later)

After Silverstone tests the car was stripped of its g/box, brakes & suspension units. The entire car being thoroughly checked over for structural failures etc. No deficiencies found in any structure
Distortion tests were carried out on the front vertical link assys and as a result certain stiffener webs were added together with mods to accept the girling caliper and disc
Extensive modifications were carried out to the body to accept tyres size 5.25 10.50 x 15 at the front and 6.50 13.00 x 15 at the rear
New wheels to accept these were drawn and made and are now fitted to the car, less inner tubes
Modification to the 5DS25 ZF gearbox including a new differential assembly with 34.5mm drive shafts replacing the original 29mm shaft which had previously twisted and a more positive method of locking the drive shaft bearings in their housings to eliminate end float. The aluminium end covers being 4.2-1 ratio altered to suit. Cast iron end covers are also available but not fitted at present
The fuel system has been completely re-piped to overcome the possibility of a further failure. The new pipe being wire braided and teflon lined
The car has been received by Lucas to suit the OPUS ignition system and the battery replaced by a standard E-Type one

INTERIM REPORT No.9 BY MJ KIMBERLEY TO WM HEYNES

"RESULTS

Fastest laps
D Hobbs - 1 minute 35.7 secs (110.1 mph)
R Attwood - 1 minute 38.1 secs (107.4 mph)

Ride
Satisfactory and wheel bounce coupling obviated

Handling
Both drivers reported inherent oversteer characteristics. Hobbs indicated rear wheel steer and Attwood roll oversteer
Tyre temperatures showed front outer wheel to be vertical, but rear outer wheel camber changed from positive to negative (at max roll) during testing. Front inner wheel camber was slightly negative, but rear inner wheel camber too negative. Adverse rear wheel camber changes are known to occur (See Report No. SP1/13/1) and new parts are awaited from ZF to rectify this.
Time did not allow the various combinations of springs front to rear to be assessed. It is felt that some improvement could be obtained with respect to 'driver feel' by the use of variations in front to rear roll stiffness ratios etc.
Both drivers complained that tyre adhesion diminished after two to three laps....Straight line running now good.

Brakes
Drivers complained of vibration and lack of deceleration at high speeds. Brake fade was experienced, and pedal movement increased with use.
Generally, the brakes were poor, and efficiency was decreased with use. The drivers lacked confidence in them - both drivers stating that lap times could be reduced by two to three secs with improved brakes.

Engine
Engine performance good after thee plugs changed, due to oiling at start of test

Transmission
As anticipated, 7,700 rpm obtained in 4th gear before Woodcote (D Hobbs), but drivers feel that lower ratio would be an advantage.Misc
Fuel System - Tanks and pickup system satisfactory. High pressure feed pipe to PI metering unit connection leak.
Gear Change - New gate satisfactory although Attwood dropped from 4th to 1st on one occasion - interlock mechanism to be checked.
Steering Wheel - Rim section diameter requires increasing.

CONCLUSIONS IN GREATER DETAIL
Although time was not available to utilise the variations in tyre secions, spring rates etc in order to obtain improved ride and handling, and reduce lap times, lack of confidence in the braking system was a severe handicap. The brake system is being stripped and temperature traces analysed to determine reasons for deterioration during running.
Rear wheel steer and uncontrolled camber change can be obviated as soon as parts are available. From the tyre temperatures shown on the data sheet, it can be seen that uncontrolled camber changes occurred at the rear wheels. Without these, the design objective od an upright rear wheel at maximum lateral G would have been obtained at the rear as well as the front. D Hobbs reported that coming out of Chapel Curve with 'tail out' attitude the car 'flicked' to the straight-ahead position. This was confirmed by the reports of two observers.
Tyres were not suitable, but Dunlop will have new tyres shortly in improved mixes, however, in the meantime, it would be most useful to try alternative makes to obtain comparisons. Wheel rim sections are very restrictive on this car and considerable improvement would be obtained with an increase of 1 1/2".

A reduction in lap times could be achieved by ...
Improved brakes ... 2 to 3 secs
Lower CW&P ... 1/2 to 1 sec
Increasing cornering ability with improved tyres and location of wheel ... 2 secs

Although this brings the lap time down to approx 1 min 30 secs the power weight ratio of the car will need to be improved considerably. Comparable power weight ratios:-
Ferrari P4 - 0.210 bhp per lb weight
Lola Chev - 0.207
Ford Mk4 - 0.206
XJ13 - 0.177

The car in its present form is much heavier than necessary and hence the power weight ratio can be improved considerably.

It is noticeable that the driver's comments regarding handling varied considerably between MIRA and Silverstone, thus indicating that the development of a car of this potential is best carried out at a suitable circuit. However, it could be conversely argued that the 'D'Type whilst winning Le Mans, never performed well at Silverstone.

INVESTIGATION RESULTS

Investigation revealed the following major points. For full details see report by E Brookes.

Brakes
The wrong master cylinders were fitted and pedal loads would have been impossibly high (280 lbs for a 1G stop). A large piece of aluminium was located behind the recuperation seal giving intermittent failure of the front brake system.
Although the DS11 brake pads were badly flaked, tapered and distorted, this would be due in part to the above mentioned system faults. Mintex M48 and Ferodo 2429F pads will be available as alternatives for future tests.
Two fractures were discovered in the pedal box but these were not detrimental to the operation of the system.

Tyres
Although D15 tyres were requested and supposedly supplied, it has since been discovered that the rear 5.75 - 1200 x 15 tyres were non D15, thus reducing lateral stability. Dowty Vibrator showed 3.8 c/sec side shake frequency with non D15 5.75's compared to 4.7 c/sec using 7.00 Mx15 D15 - and increasing 'flat tyre' feel remarked upon by D Hobbs.

Transmission
The 29mm spline drive shafts were on the point of failure and the location bearing outer race thrust washer indented. This condition increased lateral 'float' and uncontrolled camber change.

Hubs
The front hub outer bearings were also on the point of failure, due, according to the Timken and Shell Service Engineers, to pre-load. Hubs now to be reset with .002" end float. Dr Tait's calculations confirmed the above engineers' reports."

It seems that design/development of the XJ13 occupied the thoughts of its engineers - especially when they were attending events such as Le Mans. I came across some scribbled notes made by George Buck - written on the front and back of what seem to be practice times for the 32nd Le Mans event ....

32nd 'Grand Prix d'endurance et de rendement de 24 heures' - notes by George Buck

It seems the Ferraris were dominant in practice with Sargent's E-Type trailing more than a minute behind. Is it possible that Buck's reference to "P Banning of Autospray" were the people being considered to paint the XJ13?

Meanwhile, back at home, the XJ13 continued its trials with a fifth test ...

The following quoted text is © Jaguar Daimler Heritage Trust and should not be copied without their permission.

Fifth test May 23rd 1967

Mileage Start 317
5th Test May 23rd 1967
Test carried out over 163 miles. 2nd engine
General performance good
Work after test as follows
Front and rear wheel alignment checks carried out and reset to 1 degree -ve camber .15"(?) toe in 5 degrees +ve castor. No alignment change (Front)
Rear. 1 degree -ve camber .30" toein ----(remainder indistinct ?)
Front roll bar rate checked. Roll bar changed to 3/4"
Clutch slave cyl changed. Piston picked up in bore
Steer deflections measured - side drag
Electrical systems checked and rectified
Plug leads and conductors changed
Oil warning light replaced with yellow glass
Petrol filler cap modified
Speedo 480 miles

May 28th 1967 - Taken to MIRA. No test. Rain.

6th Test - June 18th 1967
Car ran over 286 miles. No major problems
The following work carried out after test
Check wheel alignment. Found to be within 1/8" longitudinal 3/16" diagonal
Check gear change linkage
Change brake pads all round
Brake balance bar ratio changed to .66 front .9 rear
Provide fresh air to cockpit
Fit 7 tooth pinion
Change front roll bar to 3/4" EN42
Fit rear roll bar 5/8" EN42
Modify rev counter drive and eliminate oil leak
Eliminate oil leak in cockpit
Fit fuel pressure gauge
Modified rear roll bar links with rose joints fitted. New housings with TufNol bushes.

7th Test - July 2nd 1967
Car ran at MIRA over 165 miles
Bedding of new pads
Work carried out during and after test
1. Seven tooth pinion removed. 8 tooth pinion refitted. This gave better steering reaction on banking.
Remove transmission unit and examine clutch throw out mechanism for source of squeal on takeoff. New throw out bearing fitted old one returned to Hoffman for test
2. New front suspension bearings with rose joints fitted
3. Change balance bar ratio .605 F / .950 Rear spacers
Examine pads and discs to determine reason for unequal braking
5. Use new method of securing h/shaft bearings in g/box using Hoffman deep groove bearings thick spacers and circlip groove widened
6. Modifications carried out on 'A' bracket anchorage and wishbone location at lower rear 'A' link bracket
7. Rose joint housing in rear wishbone o/s replaced after noting wear in hsg
8. Speedo drive with 'O' ring seal fitted
9. Engine cam cover leak. New material gasket fitted
10. 4.1 speedo with r.angle drive fitted. Original 4.5 instrument returned to Smiths for repair
11. Refit o/s door and modify locking peg
12. Improve method of securing front side valance to reduce time taken for removal
Total mileage on old speedo 957

8th Test - July 9th 1967
Speedo at start 000
Test at MIRA over 204 miles
Driver - Hobbs. Car stopped noise in clutch
1. Transmission and clutch housings removed. Clutch spacer ring disintegrated
New bell hsg. Clutch spacer ring made in LM8WP material. Fitted. New flywheel
2. Strip all brake calipers. Fit new seals all round. New front discs and rear hoses
3. Strip all hubs. Fit new seals and bearings all round. Reduce end float at rear to minimum
4. Check for end float in front suspension rose joints. All OK
All ball joint gaiters on front suspension renewed. Originals charred and split
Fit split rings to h/shaft drive flanges
7. Re-cased(?) all dampers
8. Fit new rear springs
9. Reset geometry to take new low profile tyres
10. Refit o/s door catch
11. Repair rear of body
12. Fit thermo couples to discs
13. Replace spark plug connectors
14. Fit air ducts to front and rear brakes
15. All wheels returned to Dunlop for securing of drive pegs
Speedo 204
Total miles 1157

To be continued ...

The following notes and pictures detail a selection of original documents relating to development of the original XJ13:

Preliminary drawing by George Buck - November 1963

XJ13 body - note the original, pre-1973, wheelarch profile (altered during the 1973 rebuild by Abbey Panels)

Extract from XJ13 log book - March 1967

Extract from XJ13 log book - March 1967

Extract from XJ13 log book - March 1967

The following quoted text is © Jaguar Daimler Heritage Trust and should not be copied without their permission.

"Car was run over a total of 82 miles 5.3.67
On return the following items were modified
1. Move oil cooler to front of car
2. Fit transmission cooler with pump (electric)
3. Modify engine breather system & fit catch tank
4. Modify engine lower sump panel
5.Change clutch for one with greater clamping load
6. Modify engine oil pickup and return spill oil to pressure pickup side of system
7. Return petrol tanks to Marstons for repair and investigation. Fit full clamping rings to external fittings
8. Modify front bump stop rubbers to new dimension
9. Reduce castor to 5 degrees. Toe in front wheels to 1/16" Modify steering rack to take rubber mountings
10. Bleed brake system
11. Improve method of securing rear of body to car
12. Engine removed and stripped. Found to have broken top rings.
13. Clutch unit sent to Borg & Beck. New unit with higher clamping loads refitted

Second test at MIRA on 16th April 1967

General car condition was good. After test the following work was done.
1. G/B (George Buck?) changes to give 4:1 crown wheel and pinion. G/Box number 251
2. Brake system checked over. Balance bar found to be fouling up (rectified). Wheel cyls changed. 2 1/4" dia Front 2 1/8" dia Rear. Thorough bleeding and new pads fitted. M/Cyls remain at 5/8" bore
3. Throttle sticking investigated. Found to be friction on metering head cam (modified). Throttle pedal and cable were remade and travel reduced. Load at pedal equals 11 lbs at 6" from pivot

Testing dominated by handling tests. Eventually abandoned due to rev counter drive sheared.

Third test at MIRA on 23rd April 1967 (35 miles)

Unable to test for extended period. Dewis missed gear. Suspect bent valves. Water blowing from overflow pipe in some quantity. After test, following work done

1. Remove engine and strip. Bent valves and both head gaskets blowing.
2. Shorten steering rack by .18 per side and recheck geometry to give least track interference
3. Replace 5/8" diameter M/Cyls with .7"
Complete flush of oil system including tanks. Fit new engine oil cooler No.37266
5. Fit new trans cooler twice area
Fit mechanical trans pump (not fitted)
Move existing rear view mirror to give better forward vision for driver
8. Reposition oil cooler pipes to give better access for camber adjustments
9. Remove flexible pipes on pedal box. Fit solid pipes to help reduce pedal travel
10. Gear linkage remade to increase (reverse?) action
11. Diagonal seat belts fitted
12. Inner metal panel covering engine removed to give clearance for engine intake trumpets on new engine
13. Water system revised. Header tank now feeds through 1" bore pipe direct to intake on water pump. Return from engine goes direct to rad. Small bore bleed from return pipe goes to header tank under water
14. Second set of dampers with revised bleed settings fitted
15. New white spot tyres all round
16. n/s petrol tank repaired for second time
17. Clutch slave cylinder changed
18. Drive shaft bearings changed

Fourth test - May 16th 1967 - 317 miles

Major changes from original build

Second stage engine with mechanical timing device fitted
4:1 final drive fitted
Brakes modified. Wheel cyls front 2 1/4"
Rear 2 1/8" M/Cyls .7 bore
Retraction on wheel cyls reduced to .005"-.007"
Oil cooler moved to front of car
Trans oil cooler with electric pump fitted
6.00 x 15H White Spot D15 tyres on front
7.00 x 15H White Spot D15 tyres on rear

To be continued .....

Title

Nos.1, 3 & 7 XJ6 V12 Engines

Initial Study carried out at the Jaguar Daimler Heritage Trust, Coventry on Tuesday, 30^th March 2010

Abstract

Initial conclusions of a study of original log books and associated documentation in relation to the lineage and significant events in the history of No.1 & No.7 XJ6 V12 engines as fitted to the Jaguar XJ13 prototype car. A consideration is also given to their relationship with No.3 XJ6 V12 engine.

Main conclusions drawn at this early stage are:

1.      Prior to 1978, the XJ13 fitted prototype engines’ cam drive was exclusively by means of duplex chain – and not geared drive as previously thought. It is easy to see how this misunderstanding came about because, after the removal of the No.1 engine from the XJ13 in April 1967 (necessitated by a missed gear change), it was replaced by the No.7 engine (also duplex chain-drive). In July 1967 a gear-driven cam arrangement was added to the No.1 engine while it was out of the car (some parts, including con-rods were transferred from the No.3 engine to the No.1 engine during this rebuild). The No.7 engine remained in the car until July 1978 – sometime later, it was replaced by the No.1 engine which remains in the car to this day. There is no written evidence to suggest that the No.7 engine was ever fitted with anything other than chain-drive.

2.      Although there is an unbroken lineage of the “No.1” and “No.7” engines (thought to be the only two engines to have been installed and tested in the XJ13 – both of which are believed to accompany the car today), during the course of development, major parts such as cylinder blocks, oil pumps etc were interchanged with other prototype engines. Most notable of these was the transfer of No.1’s cylinder block (almost two years after No.1 was first assembled) and associated parts to the No.3 engine.

3.      Whilst subject to the same rigorous testing as the No.1 engine (only No.1 and No.3 log books extend to two volumes), there is no record to show that No.3 was ever fitted to a car  - certainly up to the final log book entry in March 1967 stating that the No.3 engine con-rods were removed and fitted to the No.1 engine. However, a subsequent rebuild/development of the believed "No.3" engine may have taken place as evidenced by its inclusion of (so far) undocumented cylinder heads and other prototype components – including the fitment of Jaguar Mk10/420G-compatible exhaust manifolding. Further work is needed to establish the history/development of the believed “No.3” engine after March 1967.

Introduction

A paper-based initial study was conducted by the author, Neville Swales[1], at the kind invitation of Anders Ditlev Clausager[2] of The Jaguar Daimler Heritage Trust, Coventry – and the assistance of Derek Boyce[4], carried out on Tuesday, 30^th March 2010.

Permission was granted to assist in the determination of the history, background and provenance of the “No.3” XJ6[5] V12 prototype engine currently in the ownership of Neville Swales – one of the original total of six engines. The documents provided were the original engine test-cell log books and a project internal memo[7]. Also provided w as a rather intriguing internal memo giving the go-ahead to “convert a 12 cylinder engine to a V8 engine”[8] This information was supplemented by a visual examination  of the major external components of the actual No.3 XJ6 V12 engine.

The origins of Jaguar’s V12 and desire to return to international racing is already comprehensively documented by various authors – including Peter D Wilson[9], Paul Skilleter [10] and Norman Dewis[11]. Although Peter Wilson left the Jaguar Competitions Department in the same year the XJ13 was fitted with its first prototype engine, he was involved in its early development and construction.

In 1964, the go-ahead was given to produce a series of prototype V12 engines. Later, in 1965, the go-ahead was given to build a prototype competition car, the XJ13 – with an engine “specification as set out in Mr Baily’s project specification No. ZX/558/03/1”[12].

As far as can be ascertained at present, the only engine assembled to this ultimate “competition spec” was No.7 as fitted to the XJ13 on 11^th May 1967. The log for No.7 states, “10/5/67 Removed from test bed…” and, “11/5/67 Engine handed to Mr Brookes for installation in XJ13 rear engined car”. This engine replaced the previously-installed No.1 engine (itself “assembled to project specification ZX/555/01 project schedule X127”).

It is likely that No.7 engine was fitted to the car earlier than anticipated because the installed No.1 engine suffered a catastrophic failure before the 25th^th April 1967 as this entry in its log states – “25/4/67 Engine removed from car after missed gear change and revs 8,200+ causing broken tappet on No.5 A bank. Engine dismantled for inspection.” Although conjecture at this stage, the fact that No.7 engine was assembled with chain-driven cams rather than the specified gear-driven arrangement, suggests that insufficient development time was available to fit gear camshaft drive to the No.7 engine before installation in the XJ13.

All through the logs for Nos. 1 and 7 engines, there are numerous references to chain drive of the camshafts – for example:

No.1

“ … 2/12/64 … chain dampers for top chains badly worn ..”

“ … modified upper chain dampers fitted …”

No. 7

(during assembly) “ … 12/8/65 … Timing chain brackets, chains, sprockets, dampers from No.4 XJ6 …”

The single mention of gear-driven camshaft drive occurs in the log for No.1 engine (after it was removed from the XJ13 – No.1 engine, complete with new gear-driven camshaft drive was not refitted to the XJ13 until after July 1978)

No.1

“ … 12/5/67 … installed on No.8 test bed …”

“ … 26/6/67 … cylinder heads removed, stored in EXP …”

“ … 4/7/67 … timing gear to X134 specification to suit gear driven camshafts .100” eccentric intermediate shafts fitted …”

A greatly-simplified overview of the relationship between engines 1,7 and 3 is shown below:

Future Work

After March 1967 there are no further entries in the log for engine No.3. Further investigative work is required.

A detailed analysis of the engine logs for the remaining three engines (Nos 2, 4 and 8) has yet to be carried out. It is anticipated that there may be references to No.3 engine contained therein – particularly in the case of No.2 engine which contributed many parts to No.3.

Although many Jaguar ex-staff who were intimately involved in the project are no longer with us, some do remain and it is hoped to gradually build up a picture of events surrounding the project between the years 1964 and 1978. The JDHT archive is, thankfully, very well organised and managed now and it is possible that further, previously thought to be unrelated, documents may come to light.

Once a fuller history of the engine is determined, an appropriate and suitable use of it will follow. No.3 is clearly an important engine – at the heart of Jaguar’s initial attempts to design an engine that would not only power a Le Mans winner but evolve into a refined and world-beating production car engine.

Acknowledgements

I wish to record my appreciation of the friendly and open assistance given by The Jaguar Daimler Heritage Trust – in particular Anders Clausager (Chief Archivist), Derek Boyce (Volunteer Archivist), Richard Mason (Vehicle Engineer – and intimately involved with the XJ13 during its recent rebuilds) and Karam Ram (Picture Archivist).

As a long-standing Jaguar enthusiast, this is a very special and exciting project for me and I also wish to thank those many similarly-afflicted enthusiasts who have helped with their support and guidance so far – people such as Trevor Williams (TWRR), Tim Nevinson (Author and ex-Jaguar Apprentice), Paul Skilleter (renowned author), Roger Kemp (Jaguar Drivers Club), Tony Griffiths, Steve Myciunka (who shared 24 hours driving with me to repatriate No.3 engine from Germany), Tony Brown (Jaguar World), Martin Emmison (Lawyer) – and many others including posters on Autosport, Pistonheads & JagLovers internet forums.

The following pictures (many more to follow ...) show some of the external details and initial findings of the prototype V12.

The engine is in superb condition - testament to its dry storage conditions by its previous owner for the last 30 years.

Collection from resting place in Germany for the past 30 years - before almost non-stop 12 hour drive back to the UK! Customs officials were taken aback by what initially seemed to be a V12 mid-engined pickup ...

After leaving Coventry, the engine passed to Jaguar (Germany) who sold the engine to the previous owner. The previous owner displayed the engine at a Motorshow in Essen, Germany in 1998 in the same condition as when it left Jaguar (although he said he polished it!). There is a mention of the engine at Essen, as well as a picture of it, at http://www.stallard-engineering.co.uk/stories/Jaguar/ESSEN.htm

It seems the engine may have been rebuilt/restored in England by Jaguar before it was transferred to Jaguar (Germany).

The engine turns easily and looks to be complete internally. Looking into the inlet shows slight carbon buildup around the inlet valve so it was possibly run for a while before it was put into storage by Jaguar.

The cams are chain-driven although there is evidence of considerable modification in this area. It is possible there was a different cam drive mechanism at some point and it was later converted to chain drive. Interestingly, there is an external chain tensioning mechanism as can be seen in the following picture. The large nut can be used to exert pressure on the chain via a "slipper".

Device for tensioning cam chain drive.

All the currently accessible major parts have "X" (for experimental) identifying numbers and many are also complemented by hand-stamped numbers - mostly the number "3". I suspect these numbers will be recorded somewhere in Jaguar's archives and I hope to be able to access them at some point. I list some of the numbers below in the hope they may mean something to a fellow-enthusiast.

1. Front of sump - IXW 5041 (cast)
2. Front of block below water pump casing - remains of a number that could start with "X" and end with "015" (cast) (there is a stud through the middle of the number!)
3. Water pump casing - 0XW 5020 (cast)
4. Rear of flywheel - 2XW 5179 (stamped)
5. Front of block (below water pump housing) - stamped number "3"
6. Front of left head - stamped number "19"
7. Rear of left head - WM70253 0XW5641 (cast) and "T3" stamped twice
8. Front of right head - stamped number "18"
9. Rear of right head - WM70252 0XW5640 (cast) and "T3" stamped twice
10. Cams are engraved with "X" numbers / timing etc.
11. Jackshaft (distributor drive) cover - 2XW 5043 and stamped number "3"
12. Centre distributor (cylinders 7-12) - LT22357, crossed-out number below, then X2 66 (all stamped)

This engine has two 6-cylinder distributors. The plug leads are all individually numbered and it seems the centre distributor connected to cylinders 7-12. The distributors appears to be development versions and there is provision for some sort of linkage (missing) to simultaneously alter their timing. Rather perplexingly (for me anyway!), only one of the distributors has a vacuum advance mechanism - with no evidence that the other distributor has ever had vacuum advance.

Removing the right-hand bank exhaust cam cover shows it to be a substantial alloy item which is thicker than production XK cam covers. The cam bearing caps appear to be hand-finished and shaped and are all individually numbered with corresponding marks on the head. The cams themselves appear to be reground cams with quite an aggressive profile. Each cam is engraved with its experimental "X" reference number along with other numbers which may be timings. Although only a superficial examination at this stage, things such as clearances will be measured before the cams are removed.

(Exhaust headers are custom welded tube and not cast iron as in production cars).

Although a detailed examination of the sump will follow, externally there is evidence of considerable modification.

This picture also shows the rear suspension/engine mounting bracket casting. The XJ13 uses the engine as a stressed member as later practised by Lotus - this same mounting point could be used to mount the engine when fitted to a road car "mule".

The spark plugs are in the most inaccessible location! It must have been a nightmare to change them when the inlet manifolds were in place ....

More pictures to follow ......

I have been fortunate enough to acquire one of the original Jaguar V12 Prototype V12 engines. Over the next few weeks I shall post details here of this engine - its history and construction. 

I believe that this is one of only four surviving engines from the original seven prototypes. However, I have yet to definitely confirm numbers etc. Current wisdom says that there are four engines remaining - two with Jaguar in Coventry (one of which is fitted to their restored XJ13), one in a Wingfield XJ13 replica originally built for Walter Hill in the US, and my engine.

I have yet to determine the precise history of my engine - I feel a visit to the Jaguar-Daimler Archive coming on!

For now, here are some pictures of the engine "as found" - note the provision for a Mark 1 Lucas metering/distribution fuel injection unit (driven by the small cam shown adjacent to one of the distributors). I am also led to understand that, although it has two 6-cylinder distributors, these were not originally fitted to this engine (note the different caps). It is possible that a 12-cylinder distributor originally took the place of the current "centre" 6-cylinder distributor. I have yet to examine the cam drive arrangement but expect to find either all-chain or a combination of chain (from the crank) and gears (driving the individual cams from this single chain). I will post a photographic record as the examination continues.

Here are some more pictures of the original XJ13 at the JDHT ...

The sticker for the nose of the XJ13 measures 10cm x 4 cm (about 4" x 1.5") and, at the time of writing, are listed on eBay - item number 350304855583. They sell for £1.75 ($2.82) for two plus postage.

Norman Dewis' helmet inside the boot.

This and the following few pics were taken by poking my camera under the front nearside wheel

These lights are E-Type Series One Roadster - now remanufactured by SNG Barrat.

These seem to be rather poor-quality castings. Would YOU trust your life to these?