How to find compression ratio??
 

What do i need to tell my mechanic if he wants to know the compression ratio. I know the pistons are keith black hypereutectic and the crank and rods are typical 383 parts. The heads and deck were plained and the bowls are stock on the heads. Do you need more specifics to find the CR? Thanks, Brian

If you can help me find this info then i can plug it into my compression ratio calculator.

Engine bore that has been 30 thousenths over

Engine stroke with the 383 rods

Deck height with 5 thousandths removed

Regular gasket thickness

stock cly. head (cc)

and its got flat top pistons

Re: How to find compression ratio??
 

1. 4.030
2. The stroke is 3.75 in most cases.
3. I take it you mean it was zero decked, if so the deck height is 0.
4. Do you mean stock head gasket thickness? If so its either .049 or .054. I have seen both listed so I am unsure which.
5. 52cc.
6. Do they have valve reliefs? You really have to look at the spec sheet for the pistons.