can anyone do a compression check for me
59cc heads
3.905 -4cc valve relief pistons
stock ls1 gm head gaskets
forged 347 using stock crank

 

You cant type "compression calculator" into google for yourself?

I mean, I dont know what engine you have, what your bore is, what GM head gaskets you have, how far your piston sits above the deck, ..You gave us no information, all of which you have(and google)

umm...ill guess 10.45678:1

 

I got 10.606 factoring your piston in/out of cylinder as a 0. If its out of the cylinder then comp is higher, if it stays in the hole its lower.

Google is your friend.

 

Assuming your using a Mahle LS1340905F04 piston, the calculation below uses your other posted assumptions: