Hi Guys
I'm refurbishing the cylinder heads on my 3.2 Sport and would like to check the clearance of the cam bearing to make sure they are within spec.
I have the tappet clearances but I can't find the bearing sizes. Does anyone know te correct values?

 

There are no bearing inserts. If the contact area is smooth they are probably good.

 

HI RJ237
I understand that there are no removable bearing inserts however the bearing caps come in a variety of different sizes and are matched to the camshaft journals during assembly. When you take the cam off you are supposed to identify the location of each cap and replace it back on the same journal during re-assembly. My problem is I have just acquired a replacement head as mine got damaged due to secondary tensioner failure and the idiot that supplied it has sent me the bearing caps loose in a bag! So I want, by processes of measurement, to match the caps with their respective journals. I have plastigauge and a digital micrometer I would just like to know the upper and lower limits for size tolerance.

 

all the jaguar heads i have worked on had numbered caps. 0 should be the first intake cam cap with the arrow pointing towards the front of the engine. caps are labeled 0-9. Assemble the cam in the head with out any tappets and make sure everything turns ok. Be careful torquing the caps the m6's strip very easly.




This head had numbers stamped into the caps but you can easily see the factory numbering and direction arrow.

 

BTW the cam caps are not matched to the head during assembly. caps are installed and the cam journal is line bored. Caps from different heads are not interchangeable, caps from different journals are not switchable, cap directions are specific, caps are unique to their journals. with tappets removed the torqued cam should turn easily and smoothly by hand.

 

Hi MVIRGIL
Thanks for your expert advice an the very clear pic. On further inspection of both my original heads and my replacement set I can now see the numbering scheme marked at time of manufacture. Bank 1 has the inlet cam marked 0> to 4> marked from front to back and exhausts marked 5> to 9> again from front to back. Bank 2 is numbered <0 to <4 and <5 to <9
I was initially mislead by the large numbers stamped in the corner of each cap which I mistook for a bearing size. Your explanation of line boring makes perfect sense from both an engineering and manufacturing standpoint.
So looking from above :-

4> 3> 2> 1> 0> In
Bank 1 Front
9> 8> 7> 6> 5> Ex

In <0 <1 <2 <3 <4
Front Bank 2
Ex <5 <6 <7 <8 <9

I must say I am very impressed with such attention to detail and the high quality of design & construction of these engines. I am really enjoying the rebuild process and can't wait to hear this cat purrr again.
Thanks again

 

I applaud your efforts. The v8 is not the easiest engine to work and wish your the best of luck with your rebuild!

 

Not everyone is familiar with the use of plastigauge. To play safe I would take the time to check the caps. I would guess 0.001- 0.015" would be typical.

 

Have you downloaded the Engine Course 168 that I loaded into the large file area????
It is a .pdf made from my paper copy of the Jaguar Training guide.

bob gauff