This is on a 2011 5.3 with factory flat top pistons with valve reliefs. Running a 224/228 cam.

 

Ive milled .020 and had no issues. Just needed shorter PRs. Measure to be on the safe side

 

What size cam and do you know what that put your CR at?

 

I've milled .050 and been fine

 

Mine are milled. 030" anything past that can start to get intake sealing problems.

 

Thats what I've heard. What did that put your compression ratio at?

 

should be around 9.9:1 with the stock gasket (.051") on a 05 lm7 with the dished pistons. with the flattop pistons that should be in your truck you should already be at around a 10:1 ratio.

if you milled to a chamber of 61cc (~.020-.024") you would bump up to 10.5:1
stayed stock and got thinner .040" gasket and a .010" cleanup mill would net you 10.5:1 and have a better quench.

 

Not to highjack, but Im wondering the same thing about my compression ratio. I have an ly6 with the dished/valve relief pistons and 799s milled .020. Ls9 gaskets .051 i believe. Where would this put me at? 10.2?

 

my calcumalator says somewhere around 10.5:1

 

Good info here. So at what point did you guys decide on getting them milled? Sounds like you have aftermarket pistons. I have stock rotating assembly and about to tare mine apart for a mild build/update. Is it worth having the shop mill them down a bit or stick with the " just touch them to ensure they are flat " approach?