Alright as some of you may know I have been in the process of building a new 350 for my car. Well I am getting close to have all of the parts I need to finish the swap and I was trying to figure out what my compression ration would be. I have an 010 mid 70's truck 350 with 76cc heads and I think they had 8:6:1 compression stock. I dont know that for sure so I hope someone can confirm that for me. well My question is what will it be the stock 64cc vortec heads I have on it now. I was thinking it would probably be around 9:3:1 (just a guess). But if any of you guys know what it would be for sure I would appreciate if you help me out on this. Thanks.

 

10 cc's of head volume gives you approx. 1:1 change in compression ratio: If you have 11:1 with 74cc heads, you'll have 12:1 with 64 cc heads (approximately)

 

www.chuckschevytruckpages.com should help you with the engine specs.

www.mortec.com will help you with the casting numbers.

If it truely is 8.6:1 with 76 cc heads, 64 cc heads would change it to ~9.7

 

A typical 70s truck motor, with typical 76cc 882 or 624 heads, had about 8.2:1 CR.

With 64cc heads you're probably right close to 9:1. It's hard to be exact since there's so much tolerance and variation in block deck height. It also would be strongly affected by the head gaskets you used.

 

So true. The variations will make it hard to get exact w/ the numbers, but you can get a close representation on what you would have.

 

Man those engines had 8:2:1 compression huh. That sux, well I have 882 heads and its the stock deck height, also I will be using the standard head gasket they use on those engines. I was wanting to have about 9:5:1 compression. I guess I will just have the heads milled a little. I will probably do some research on the sites that were posted previously. Thanks for the help guys I appreciate it.