1970 350 compression
February 11th, 2013, 11:59 AM
#1
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Location: Chisago City, MN
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1970 350 compression
Hello everyone, I have been searching for the stock compression ratio for my 70 350. I am bringing the engine to a builder tonight and want to know what the original compression ratio was. It is the numbers matching engine for my cutlass supreme vert. So I am sure it was the 310 hp V8 option engine. The only thing I could find doing research was a thread on this site that said 10:25 to 1. Is that correct? From what I have read you don't want over 10:1 to run todays pump gas. Its not that I don't trust the guy I'm bringing it to but rather this will be the first time I've met him as I got his number through some other guys I know. I took the heads off and from what I can see I am not sure it even needs to be bored out now, I was expecting it to need that but there are no ridges that you can feel in the cyclinders. If that is the case I assume it would be a good Idea to re-use the stock pistons? So if that is what I do, is the compression going to be too high? Any advise would be appreciated Thank you
February 13th, 2013, 08:42 AM
#3
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Mine was the stock 4-barrell 310 horse. Turns out my cylinders do not need to be bored and my pistons are re-usable as well. Do we need to get the compression down so I can run pump gas? Should I get lower compression pistons, or will thicker head gaskets get me down under 10:1?
February 13th, 2013, 09:23 AM
#6
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Location: Shorewood, Il.
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Re-jet the carb a little richer, lower thermostat, and timed by ear [-2 degrees when you hear pinging] should do it, and hardly effect performance.
Maybe ask Cutlass EFI for a cam suggestion.
Maybe ask Cutlass EFI for a cam suggestion.
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