so when i put my engine together about a year and a half ago i think i did the math and my compression came out to like mid 9s:1. i am in the market for new heads now and i just wanted to remind myself of the actual compression and see whats the lowest cc i can go to keep it safe BUT
after using about 3 of the online CR calculators i always got the same cr of about 10.8:1, i highly doubt thats right so i wanted to see what you guys thought.

I just have a stock bore 350, flat tops with 4 valve releifs, oem head gasket and 64cc heads that were shaved 1cc off. The block, as far as i know, is completely stock and has never been decked, stock 350 crank. and stock 5.7 rods

If you guys could let me know what you think my cr ratio is close to, i would really appreciate that. thanks in advance

 

If it's designed right, high 10's can be done on pump gas.

My guess you're in the mid 9's. Depends on gasket dimensions and size of the valve reliefs, assumed with stock deck.

 

thats what i was thinking, i didnt think 10s sounded right with my stuff. headgasket i think its felpro? idk, but i will probably 0deck the block when i replace the heads, any suggestions as far as decking goes?

 

I'd guess you're in the mid to high 9's. My 355 with flat-top 4 valve reliefs, no block decking (I think they ended up about .020" in the hole), .028" compressed gasket thickness, and the 64cc vortecs came out to 9.97:1. Most head gaskets are a little thicker, so 9.5-9.8:1 should be pretty close.

I'd leave the call on decking the block up to the machinist. If it's not straight/flat, definitely have it done. If it looks good to him, I wouldn't bother (unless you want a higher CR or more squish).