I'm changing the head gasket on my 1959 235, and I cc'd the combustion chambers and measured the valve sizes, in case anyone's interested.
I got 84 cc's volume in the combustion chambers and the valve sizes were as follows:
Intake: 1.688"
Exhaust: 1.313"
I had to guess on the head gasket thickness and diameter, since the cylinder holes are not circular in thea head gasket. And I guessed at 0.039" compressed thickness. I also guessed that the pistons are down 0.025" in the holes at TDC.
But what I calculated was a compression ratio of 7.81:1. Slightly lower than the 8.0:1 that the book says it should be, but it could be in some of my assumptions.
There is a lot of room for improvement in this head design. I can see why Leo Sanducci adapted a pair of small block Chevy AFR aluminum heads to his stovebolt. (By whacking off 1 cylinder each and welding them together).
I can imagine if you can get a modern cam, head, induction, and good exhaust, you could pretty easily double the output of an inline 6.
