Engine builder built it to be 13:1 but after I got the job number off the bottom of the piston I called je there 15:1 that explains why my tune ups are a mile off. Block is 0 deck it has grp aluim rods and a comp height of 1.177
I ran two fogger son mine one with a 32 jet and one with a 24 and the bore size was 4.040. I was having trouble with the thinner head gaskets lifting between 4 and 6 so I went with the thick gasket and I feel as though the extra thickness gave it just a bit more of a cushion in between the cylinders. Did it? I don't know, but it worked. BTW block has the o-ring and the heads have no receiver groove in them.