What head is this?

[Gene F]

Originally Posted by JayJay

As Vince Falter's most excellent web page notes (see Stickshift's post #3) there are a lot of aftermarket heads. I have a "Model A" aftermarket head on my '31, which apparently came in both 4.2 and 5.2 configuration. I pulled the head off last week to change the head gasket and sure enough, I have the "high compression" version. I put that in quotes because a 5.2 compression ratio ought to put cylinder pressure somewhere in the 70's psi. Well, I have 80s and 92 in one cylinder! I suspect that the block and head have been decked sometime in the past, the engine is 0.080" overbore so it likely has been rebuilt at least twice and the block possibly decked each time. The head appears flat, I used a 0.003" feeler gauge and a straightedge and could not get it in anywhere, either lengthwise or crosswise. So I'm going to put it back together (after I get the broken stud out, of course...) and run with it.

JayJay

I have a Brumfield. So how do you measure these things for compression ratio?