The largest and best supported Jaguar cars enthusiast site on the Internet!

Serving Enthusiasts since 1993
The Jag-lovers Web

Currently with 3,166 members

XK Engine Marking ('64 3.8 S-type)

XK Engine and Head Markings 

The purpose of these pictures is to illustrate where identifying markings are on the XK engine. I apologize that the example used here is not from an XK, but is from a '64 3.8 S-type. I believe that there are enough similarities that the pictures are still relative and should be able to serve as a point of reference in our e-mail discussions. If anyone has pictures of his/her engine I would be glad to add them to this page.

Head Markings

Front of head showing serial number. This should match the serial number stamped on the block, '7B50561-9', just above the oil filter (see block pictures below). The '7B' identifies it as coming from an S-type and the '-9' confirms 9:1 pistons. Pay little attention to the colors here. The photo's were not color corrected and also, they will vary depending on your monitor and/or printer.

Click on picture for full size view

Front of Head w/Serial Number

This head is a 3.8 'B' head and painted medium metallic blue. Not all 'B' heads were blue. There have been several reports of 3.4 'B' heads with 'duck egg green'. On the rear of the head is a boss and stamped on the boss on this head is 'HH65.' John Elmgreen would like to know what number is stamped on yours. He is trying to correlate these numbers with engine numbers. There is also a small '2' which was cast and not stamped on the head. Is this in the same location as the 'C' mark on some 'C' heads?

Click on picture for full size view

Head - Top View

Two markings. On the top surface near the rear is a boss. Clearly stamped on this boss is 'HH65.' Again I don't know the significance. On the rear surface is the stamping '220 JAG.' This font is very small by the way and difficult to see.

Click on picture for full size view

Head - Rear View

Bottom of head showing casting marks. The numbers on the top preceded with 'C' I presume are part numbers. I don't know exactly why there would be two of them. I have no guess as to the meaning of the other numbers. The '2' on the lower left is similar to the '2' on the top of the head. Next to the '2' is the logo made up of a Y on top of a W (similar to the familiar VW logo). I presume this is the logo of West Yorkshsire Foundry mentioned by John Elmgreen from Viart's book.

Click on picture for full size view

Bottom of Head

Left (exhaust) side of head. I painted this area because there was a significant amount of the original paint there. There were no traces of paint on the right (intake) side. This may be due to the size of the areas. The right side is small - the distance between the edge of the exhaust manifold and the cam cover edge (1-1/2") is much greater than the distance between the intake manifold and the cam cover edge (3/8"). Keep in mind this is from an S-type. I do not know if all XK heads were painted similarly.

Click on picture for full size view

Head - Left Side

Some other curious markings.

  • Cast 'i' below breather hole.
  • 230 JAG stamped on two head bolt landings.
  • '26' and '12' on left side of head. Quality control mark?
  • T7 stamped on left side of head. Quality control mark?

Block Markings

This picture is of the right side of the block highlighting the serial number (7B50561 - 9) stamped on top of the flange for the oil filter attachment. Shown with oil filter assembly removed. I understand that the '7B' prefix to the number designates this block as coming from an S-Type. The '-9' suffix designates that this engine was assembled with 9:1 pistons. On the side of the block you can clearly see that this is a 3.8 liter displacement engine. On the top right you can see the Jaguar part number (C22250 FF).

Click on picture for full size view

Right Side of Block

On the lower portion of the block are several casting markings shown in the enlargements. I don't know what any of them mean. The last one is '13-12-6x.' There appears to be a digit following the six. It looks like it might be a three. This may be a date code for the block. This is out of a 1964 S-type. I have no idea what the 'HF' or the 'U' signify.

Click on picture for full size view

Left Side of Block

Stamped on the upper right corner of the block is 'BG949.' Again, I don't know the significance. It doesn't match any other numbers that I am aware of. It is stamped and not part of the casting.

Click on picture for full size view

Rear of Block

This is the mating surface of the block to the oil pan. More specifically, the flange near the right hand side of the bellhousing. I found this stamping to be unusual. To be seen the oil pan must be removed. It says '247 JAG.' Again, I have no idea of it's significance.

Click on picture for full size view

Bottom of Block near Bellhousing

Upper left corner of block and timing chain cover. Stamped on both are the letters 'ULU.' This is also the same as the prefix of the marking stamps (no pictures) on the bottom of the block marking each of the main bearing caps (ULU1 through ULU7). Coincidence?

Click on picture for full size view

Left Side of Timing Chain Cover

If you have any questions or comments send e-mail to:
Main Page Back to the Library


Please help support the move to the new site, and DONATE what you can.
A big Thank You to those who have donated already!



Go to our Homepage
Improve your Jag-lovers experience with the Mozilla FireFox Browser!

  View the latest posts from our Forums via an RSS Feed!

Jag-loversTM Ltd / JagWEBTM 1993 - 2023
All rights reserved. Jag-lovers is supported by JagWEBTM
For Terms of Use and General Rules see our Disclaimer
Use of the Jag-lovers logo or trademark name on sites other than Jag-lovers itself in a manner implying endorsement of commercial activities whatsoever is prohibited. Sections of this Web Site may publish members and visitors comments, opinion and photographs/images - Jag-lovers Ltd does not assume or have any responsibility or any liability for members comments or opinions, nor does it claim ownership or copyright of any material that belongs to the original poster including images. The word 'Jaguar' and the leaping cat device, whether used separately or in combination, are registered trademarks and are the property of Jaguar Cars, England. Some images may also be Jaguar Cars. Mirroring or downloading of this site or the publication of material or any extracts therefrom in original or altered form from these pages onto other sites (including reproduction by any other Jaguar enthusiast sites) without express permission violates Jag-lovers Ltd copyright and is prohibited
Go to our Homepage
Your Browser is: CCBot/2.0 (, IP Address logged as on 24th Sep 2023 04:19:10