Piston ID

PRH said
3.38 + 2.88 = 6.26
6.26/2 = 3.13

The volume of a 3.13 x .300 hole is 37.8cc

Subbing in a 38cc dish instead of the 51cc dish put the CR at 7.4 for 88cc heads, and 7.9 with 78cc heads (still assuming a steel shim gasket and .050 deck i

I added half the difference between the two and came up with 3.63 when i should have subtracted it to get the 3.13.