Kaane

iTrader: (2)

I just picked up a low mileage LS3 short block for my M3 project after my LS1 suffered bottom end issues. I already bought LS3 heads.

I will be running a 222/230 .597/.600" 114LSA +2 Cam. Is it worth milling the heads to pick up a bit of extra compression? How much could I safely mill?

Mike454SS

iTrader: (4)

I guess it depends if you intend to do any other head work at all...or just mill them...and then where you want your compression ratio to be.

What fuel do you want to run? How thoroughly are you going to tune it? Will you do any chamber and port work? Do you want to run GM head gaskets?

Kaane

iTrader: (2)

No port work. Would like to hit 11:1 compression, I could run 0.040 head gasket and that should almost do it. It will have a full custom tune. 91 octane only.

bww3588

iTrader: (49)

Going to be tough to hit 11 to 1 with stock pistons and the huge valves. You quickly run out of real estate for The valve and piston to fight over.

Tainted

iTrader: (9)

Pat G warns of milling LS3 heads to much as you will run into PTV issues.

I suggest you do a bit of research and measure your PTV clearance with some clay

Kaane

iTrader: (2)

I am probably just going to run a thinner gasket and leave the heads alone. Cometic 0.040 should put me at 11:1.

eyerideakfx400

Measure PTV clearance before milling. Install the cam your gonna use, weld up two lifters, (plunger) or take your lifter apart and remove the spring and put some washers in there or a nut so it will'nt collapse and install head. Install intake and exh rocker on 1 cylinder. Turn your rocker arms till you get 0 back lash.(do not tighten) Get some playdough or clay and put some on your piston and see where you stand before you mill so you know exactly what you can take off.. min safe clearance from what I understand is .050-.080 so if you have .130 PTV clearance before mill, you will be able to drop .080-.050 I think every .006 of mill is roughly 1cc.