M750 1998 head orings

[matty450]

I have taken the heads of  and found that the o rings on the return oil ways have had shims / washers put under the o rings, i am guessing this is not normal ?? maybe someone has had oil leak issues in the past and has tried to pack the o ring out a bit, although this is only return oil under no pressure ??

[matty450]

Can someone help !! Should i have an o-ring recess on both the head face and the barrel face ? ( oil return holes ) as both recesses are approx 1.6mm deep = approx 3.2mm, the o-rings are approx 2.6mm therefore too small , hence why they have been shimmed up to make a seal, surely this cannot be right, has this engine been bodged up with different year parts or should this year have thicker section o-rings ( approx 4mm )

[matty450]

There is a 4Y stamped into the casting along with what looks to be a date code of 12/95 ,i guess dec 1995, could i have early heads on later barrels ??

[Howie]

The O rigs are supposed to fit without shims.  I don't know if there were any changes in O ring size over the years.  Maybe order O rings for both year engines and see what you get?  There are two different size O rings, the one that goes around the bushing is different.

[matty450]

The O rigs are supposed to fit without shims.  I don't know if there were any changes in O ring size over the years.  Maybe order O rings for both year engines and see what you get?  There are two different size O rings, the one that goes around the bushing is different.

Do you know if there should be a o-ring recess on both head and barrel faces ?

[Howie]

Sorry, I don't remember.

[matty450]

Looks like i may have 1995 SS heads on my 1998 bottom end,looks like they changed which face had the o-ring recess in over the years.