Abdullah

iTrader: (2)

i just finished porting the stock LS1 heads for stock valves. it didn't take too much effort just opened up the bowl a little bit removed thr rocker arm hump in the intake runned and lightly polished the floor and short side radius, almost same thing for the exhaust port. i expect for the flow to be 260cfm/200cfm with good port velocity.

now i want to increase the compression of the engine by milling the LS1 heads. what i know the stock compression is 9.9 or 10:1. how safe can i go with the stock GM gasket which i knew it has a thickness of 0.058" from www.LS1speed.com? can i mill the heads to say 0.045" safely without the valves hitting the pistons? i want to achieve 11:1 if possible? 10.5:1 compression is OK to me. i know with the stock heads the chamber is 66cc. if i mill the heads 0.045" what would be the chamber volume?

yes, i forgot to mension that i want to use either the texas speed 233/239 R2 cam. if i can safely raise the compression to 11 then i want to use the MS4 cam.

thanks for help.

Rhino79

iTrader: (7)

Milling .045" is going to drop the chamber volume to around 58.5 cc.

Abdullah

iTrader: (2)

thanks for the relpy. is it safe to mill the heads 0.45"?

at 58.5cc chamber volume what would be the compression with stock pistons and stock head gasket?

Rhino79

iTrader: (7)

.045" is fine, I wouldn't go more than about .050" though. With stock pistons and gaskets that's gonna put you close to 11.0. You will need to check piston to valve clearance though just to be on the safe side.

Abdullah

iTrader: (2)

how to check for piston to valve clearance on LS1?