I have those pistons, that are 27 in the hole. With a 65cc head came out to about 9.6 to 1 if one uses a 39 gasket.
I went down to 57cc and went with thinner gasket to get to 10.5

Last edited by B3422W5; 08/23/17 03:11 PM.
69 Dart GTS A4 Silver All steel, flat factory hood, 3360race weight
418 BPE factory replacement headed stroker, 565 lift solid cam
Best so far, low 10.30’s 1/4
1.41 best 60 foot
6.56 at 104.17