Title

Nos.1, 3 & 7 XJ6 V12 Engines

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

Abstract

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

Main conclusions drawn at this early stage are:

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

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

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

Introduction

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

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

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

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

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

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

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

No.1

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

“ … modified upper chain dampers fitted …”

No. 7

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

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

No.1

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

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

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

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

Future Work

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

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

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

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

Acknowledgements

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

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