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Old 01-13-2016, 03:01 PM   #113
davepl
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Join Date: Aug 2006
Location: Redmond, WA
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Re: Starting my engine build

Quote:
Originally Posted by Mrturner1 View Post
so if it does have stock pistons, what would the compression ratio be with 67cc chambers on the heads?
You'd need a depth gauge (depth micrometer or similar) to know how far down in the hole the piston is; generally that's actually a measurement of how tall the deck is, if you think about it, because the rods and pistons should be standard.

But you need to know that as well as the compressed thickness of the gasket AND the cc size of the reliefs in those pistons.

You can probably get close talking to a head company and telling them it's a 350 with flat top pistons with 4 little valve reliefs and that the engine has been rebuilt before. You'll probably assume it's been cut to a flat deck (piston top flat with the deck). Then if the deck is actually any higher you get slightly lower compression than you thought. Better than too much.

If you have aluminum heads and are shooting for 10:1 or something (no idea) and wind up 9.8:1 you'll never know and the horsepower difference is close to 0.
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