Originally Posted by 95chevy406
The guy was running vortech heads.i have a set of 64cc 87 350 heads shaved .040 with ss valves and steam holes drilled.with the pistons and heads i have the compression will be around 10.9:1
That is too much compression. For pump gas and iron heads about 9.5:1 will be on the safe side. You really need to measure the chambers of those heads. You cannot figure compression ratio without knowing piston head volume and cylinder head chamber volume. If your heads were 76cc chambers and you milled .040 from them you probably have about 67 cc chambers. With a 7cc flattop pistons and .015 head gasket you would have about 9.792. You might have to use 89 or 93 octane gas depends on how your timing is setup. If you have a motor with 18cc dished pistons and using those heads your compression would be about 8.760. Factory pistons with the same heads and gasket would be 8.443 compresssion ratio.