Engine Build Dates? MKII 3.4 8:1

(Timothy M Fox) #1

Hello, Does anyone have access to the build dates for MKII 3.4 8:1 engines?

Looking at Nigel Thorley’s book, Original Jag MKI / MKII (PG. 62) engine number KG6738 was the first engine produced in June 1961. KG 9884 was the first engine to be produced in August 1961. My car is fitted with engine KG 7242 8 which matches the compliance / build plate. The car was produced on the 11th of July 1961 and dispatched on the 21st of July 1961. According to Jaguar’s Heritage Department my car was “originally” fitted with engine number KG 9937 8. The problem is that that engine KG 9937 8 was built in mid August! The engine in my car KG 7242 8 was built in late June 1961!

Which do I trust, the compliance plate or the Heritage Certificate?


(Brian T) #2

Hello Tim,

Our 3.8L MK2 block has the casting date cast into it. The date is located on the exhaust side of the block just in front of the dip-stick boss. Our engine number matches the data plate and is corroborated by Heritage certificate. It’s interesting to note that our block was cast on the 5th day of July, 1962 (5-7-62). Our car wasn’t completed until the 10th day of October 1962…3 Months after the block was cast.

(Rob Reilly) #3

Ask JDHT for a review of your certificate. They may have made a mistake.

(Timothy M Fox) #4

Hi Rob,

I did ask but received a very unsatisfactory response. Basically they told me that they have the only truly accurate records and that everyone else has inaccurate records. I guess it’s like any institution with a vested financial interest? They were still unable to explain just how a July completed car could be fitted with an August manufactured motor!

By way of yet another example, my MKIV was originally fitted with a red interior (which I have) and which the original Delivery Note from the original Dealer confirms. JDHT issued a “Certificate” saying that it was manufactured with a Suede Green interior!

I’m quite sick of this “Certification” process.



Timothy Fox


(Rob Reilly) #5

Possibly KG7242-8 failed a test, KG9937-8 replaced it just before the record book entry was made, then KG7242-8 caught up with it and was put back in. Or KG9937-8 was designated as a replacement but was later found to be not necessary as KG7242-8 was repaired in place.
Or your ID plate could have been changed when KG7242-8 was installed later.
Compare with other near car numbers on saloondata.com and maybe you can get a better idea which to believe.

My '38 SS original seats are beige and somebody overdyed in red, but I can see beige underneath. My 120 original seats are suede green but overdyed with black, again the green is visible underneath.

(Timothy M Fox) #6

Hi Rob,

Thanks for the thoughts I shall look at Saloon Data now. The gearbox is correct for the car and matches the Build Plate and the Heritage “Certificate”. It is also an overdrive car and that all matches.

As for the seats in the MKIV, they are the colour they they left the factory, no doubt about that. They are also all original Jaguar Factory fitted leather and trims.

Do you know how to contact Nigel Thorley? I’m assuming he’s still alive?



(Paul Wigton) #7

In the past, and on this very list, that has been shown to be a less than accurate assertion.

(Ian) #8

You have the car , engine , and id plate , that sound right to me , that’s 3 to 1 Heritage Certificate ,

(Timothy M Fox) #9

I’m with you, Ian.

However these “Heritage Certificates” have taken on an air of authority which they most likely don’t deserve. The issue remains that buyers seem to place an undeserved value on the Certificates which affects the value of the car, even if they are fallible.




Hello Brian T,

Your block having a date some 3 months before the car was built was not only production normal but good engineering. Large castings were traditionally left to “weather” (de-stressed) preferably outside, before any machining took place. In the best companies this included crankshafts.

In the case of cylinder blocks fitted with liners 3.8, 4.2 etc but not 3.4 it is sensible to weather the block after liners are pressed in, and before boring. Such de-stressing is vital but unfortunately not understood by so called modern engineers.

(Paul Wigton) #11

Given the longevity and durability of modern engines, I think it’s safe to say modern engineers understand precisely what they are doing.

(wardell) #12

Still alive as far as I know. He was very involved with the Jaguar Enthusiasts Club here in UK.
Suggest you email them.



Unfortunately, we are not dealing with modern engines here but engines with 50 and 60 years old castings.

On a workshop level modern technicians, mechanics or engineers, call them what you will, are not trained to cover a wide spectrum of repair techniques. In general, those that know such techniques retired some time ago.

On a manufacturing level I see plant fixture manuals to combat design faults getting thicker and I see engineers precisely trying to solve problems that were fixed 60 years ago and more………in short redesigning the wheel when a short read of history would have solved the issue.
If modern engineers had taken more time to think, instead of charging forward, I would not have needed to travel to 50 plus countries to sort out automotive and military problems.

However, we can agree to disagree.

Apologise to anyone….I have not intended to hijacked this thread.

(Timothy M Fox) #14


As I started this thread with my question I thought I might say that the talk about good engineering practice was very helpful. If engines were made three months in advance of being machined up ready for completion that makes good sense to me. My initial question related to the timing at which engines were fitted to cars. The engine that was said to have been fitted to my car shouldn’t have been fitted until August 1961 according to Nigel Thorley in his book. The engine in my car at present would have been fitted in July 1961. My issue remains that if Nigel is correct then Jaguar Heritage is wrong.

Cheers and thanks,