Thread: i need some compression help here plz!!!

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k i'm trying to figure out what compression ratio i'm gonna be running and none of the calculators are adding to to my book specs... i got a sbc 350 and i'm putting speed pro flat top 2 valve relief pistions .040 over(H631cp40)...according to the speed pro book i should be runing 10.45 with 58cc heads and mine are
60cc so i know it'll be at least 10:1 which my cam recomends... and with stock deck height... the calculators are saying 11-12:1 and thats gonna be way to high for pump gas... i'm runing the composite felpro perma torque head gasket... stock rod length and stroke...my engine builder mentioned decking the block but that will put me higher...can anyone give me some help i could really use it... the book lists that number with a deck clearence of .025 and compression distance of 1.56

I would say it is best to get direct measurements if possible. It is going to be out of service longer, so if it is your daily driver I am sorry. It sounds like you have a target CR, so find out what your piston deck height is going to be at the desired squish. Then what pistons and gasket will get you close to target.

Denny, that's kind nof a personal question dontcha think?..........LOMAO.....Sorry, just had to get silly for a second.

Yes,direct measurements are the only safe way to find out because some decks are out of square and just doing the calculation on paper may be off quite a bit.
Do a mock up with the 4 corner pistons in and check at the 3 o'clock and 9 o'clock positions (FRONT/REAR).
Somewhere around 10.5:1 sounds about right but that could be a wild guess that turns out to be a .010-.020 mistake.

Lol!!!!lol!!!!