964 head markings for height
 

Trying to determine head height group. My part numbers were cut off at what appears to be the last digit of 5. They are all oem factory original 89 heads. They were machined by the dealer under warranty to update to the head gasket use. Just trying to determine if there is another way to check group height. The only difference is that some are marked with 1 and others with 2…… however, I’ve seen oem heads that do not match those numbers across a bank (example from an ad, still attached to the cam tower with oem style no head gasket. So I’m guessing they are not height groups. Are there any indications of height group other than the part number? They were all mfg in 89 and are the same in every other way.

Thanks

Pic from ad
 

Here is an example….http://forums.pelicanparts.com/uploa...1680764299.jpg

Only height group numbers I know of are either 5 or 6 and they’re on the cylinders not heads.

If there was a cyl. head height group it went out the window when the dealer machined the heads for a updated cylinder with a CE seal ring but as DP mentioned there is no group heights on the cyl. heads only the cylinders.
The size dimensions of the cylinder head when new are 84.48 mm +- 0.02
Richard

The only head height measurements I’ve seen are on race heads like RSR or 935 heads. These 935 heads were 3.2 and stamped at the bottom of the intake port 86.52. Measured from cam tower surface to cylinder sealing surface. I machined them down to 84.50 which is a more traditional dimension. The number is used to determine how much machine surfacing has been done to the heads. Never seen any stamping on production heads but a couple of cuttings is usually acceptable.http://forums.pelicanparts.com/uploa...1680840336.jpg

you can measure them

Easy way to measure and accurate would be to find a surface plate and gauge, local machine shop.

Those numbers are cast into the heads. Likely means something to someone at the foundry (ie 2nd shift or 2nd revision or employee #6). Castings of the period simply lack the precision to be cast in high tolerances such as cylinder head height down to 0.25mm.

place the cylinder heads individually onto a single cylinder on a very flat surface. With a height gauge measure down to the surface that seals the head against the cam housing. That distance, between where the cylinder mates and the cam housing mates, is your critical distance. Bob