I'm trying to buy new pistons for the 427 I'm building to replace my 402...only problem is the heads I'm gonna use are STILL ON the original motor <doh>. I need to know what type of heads I have to get the proper compression ratio with the new piston. The heads are 1970 402 heads from a 1/2 ton GMC pickup. Does anyone know if these original heads are open/closed and what size combustion chambers they have?? If one of you experts knows the answer off the top of your head, it would be much quicker than pulling a head off and trying to find the casting number...
Mega-thanks!! JB
