Blog posts tagged with 'technical'

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.

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.

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 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!

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 ….

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 ....

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 .....

Here are some pictures showing how a home-made device can be used to easily separate V12 heads from the block.

Having studied Kirby Palm's excellent technical summary of the V12 (downloadable for FREE from http://www.jag-lovers.org/xj-s/book/XJS_help.pdf), and having listened to some tales of woe from others who have struggled vainly to separate the heads from the block, I decided it would be well-worthwhile making up a device to simplify head removal - particularly as I have at least two engines to rebuild. Also, when I went to collect this engine, I was shown a block where one head had been completely removed and the second was stuck fast - even though there was 3 inches of fresh air between the head and the block. The owner had tried over many months to separate the second head (without the benefit of "The Beast" but all attempts had failed. He was even considering having a hollow reamer made that he could slip around each stud - but I suspect this is "clutching at straws". Perhaps, if I am feeling generous, I may pay him a visit with "The Beast" in tow.

I have probably spent more time making up such a device than actually working on the engine, I feel it was time well-spent! I have christened the head-removal device "The Beast" because of its size and weight :)

I must add here that I have become an avid reader of the V12 forum on the "Jag-Lovers" website. Over the last few weeks I have learnt much about the V12 from its contributors - many of whom are very experienced in Jaguars in general and the V12 in particular. I unhesitatingly recommend you subscribe to this forum if you are contemplating a V12 rebuild - the members there are invariably helpful and willing to pass on the benefit of their experience. You can visit Jag Lovers by clicking HERE.

The engine

The "flat-head" V12 in the photos had been stored in various garages/lock-ups for the past 20 years or so. I was told it was removed from a XJ12 saloon. Because of its history, I was anticipating difficulty in persuading the heads to leave the block .... The first thing to greet me when I came to remove the head nuts was just how many there are! Having been used to the relative simplicity of the XK 6-cylinder iron block, it seems I will have to develop the patience that is needed for "12 of everything" .. or should that read "24++ of everything"? Of course, it is important to remember to remove ALL the nuts holding the head down - including the ones attaching the head to the top of the timing-case. "The Beast" is more than capable of pulling a stud out of an alloy head if a nut is left attached.

Incidentally, I discovered that there is no need to make up a special tool to hold the camshaft sprockets in place during head removal if you happen to have a couple of suitable external circlips. I found that by placing circlips into the grooves already machined into the end of the sprocket spindles, the spindles can simply be dropped over their respective retainers. There is also no need to slacken the chain using special tools if you simply fasten one of the sprockets to its holder so it remains out of the way while the head is removed.

"The Beast"

"The Beast" is fabricated from two sturdy 3/4" steel plates. The top plate fits over a series of threaded bars that are welded into the bottom plate.

Step One - attach lower plate.

Place the lower plate on the head so that the camshaft locating studs protrude through it. It can then be fastened down using the original nuts and washers. Please bear in mind that this is an alloy head and do not over-tighten these nuts!

As can be seen in the next photo, the studs at the front of the engine are in different places left to right. I don't know if this is a peculiarity of all these V12 engines? The plate covers all the camshaft studs on the left-hand head, but misses the front pair on the right-hand head. If I was to make another bottom-plate, I would add extra length and holes to accommodate this left-to-right difference..

Step Two - add steel rods

Drop the rods (I used stainless) through the bottom plate so that each rests on a cylinder head stud. The diameter of the rods is slightly smaller than the cylinder head studs and they are chamfered to facilitate them following the studs through the head.

Step Three - place upper plate

Place the upper plate over the threaded bars and, using the small socket-head screws, level it making sure all the stainless rods are in contact at both ends.

Step Four - fasten upper plate

Check the plates are parallel to each other and fasten using long nuts/washers on the threaded bars.

Step Five - remove the head.

Remove the head by tightening each double-nut the same number of turns, in rotation around the upper plate. The whole operation took under an hour for each head and required very little effort - in fact, it was quite therapeutic and satisfying to see the head gradually slide up past the studs. The hardest part (once the head was lifted almost clear of the studs) was lifting the head complete with "The Beast" off the engine.

I could be persuaded to loan "The Beast" out when I am finished with it in return for a small donation towards its fabrication costs.