Cylinder head height tolerances

[irover]

Hi

Just had my cylinder heads flycut. I was wondering what the tolerances are in height between the top and bottom of the cylinder head, i cannot find this information anywhere.

It is quite crucial i suppose since the cam box is bolted on the heads and the heads sits on equal height cylinders. If the heads aren't the same height then i will get problems with oil leaks or compression leaks.

Thanks

Peter

[ChrisBennet]

Welcome to the board Peter!

I'm sorry I don't know the specs either. Put the cylinders and heads on the motor (no gaskets) and put a machinist's straight edge across the tops. Differences in height will pretty obvious.
If they aren't even the cams will bind.
-Chris

[Fishcop]

Any differences can be negated by cutting the spigots on the case, different spacers under the cylinders may help also.

[ChrisBennet]

Everything should be made square. The machinist who flycut the heads should have made them all the same height. If the case spigots aren't the same height you should deck the case.
-Chris

[irover]

It's a 930 turbo and it doesn't use head gaskets. What is acceptable differece in height when laying the straight edge across? 0.1 mm? Or one tenth of that? Just have no idea. All measures have limits but i'm really stuck on this one.

thanks for your help and for welcoming me here!

Peter

[ChrisBennet]

Originally posted by irover
It's a 930 turbo and it doesn't use head gaskets. What is acceptable differece in height when laying the straight edge across? 0.1 mm? Or one tenth of that? Just have no idea. All measures have limits but i'm really stuck on this one.

thanks for your help and for welcoming me here!

Peter

I was thinking of the base gaskets. If it was me, I wouldn't want to see any light under the straight edge.
-Chris

[irover]

that's 0.01 mm then. Thanks.

Peter

[ChrisBennet]

I was looking through the factory 964 manual last night and it specifies .02mm as the tolerance.
-Chris

[irover]

do you think its the same for the 930?

I have the factory manual for the 930 but cannot find this value.

Peter