matrixiskool

iTrader: (12)

If I want to get to 11.5 compression how much should I get my stock brand new ls3 heads milled by? I have Wiseco -3cc flat top with valve reliefs cut in. I also think I could get a thinner gasket so I only have to mill the heads a minimal amount.

Sales2@Texas-speed

iTrader: (5)

Assuming you have the 4.030" bore pistons for that 408ci and the piston at 9.235" zero deck, to get 11.5:1 static compression you could go 66cc chambers and GM MLS gaskets, or .040" gaskets and 68cc chambers.

matrixiskool

iTrader: (12)

Alright then that was easy haha thanks. Ill go with the 68cc chamber and .040 gasket then. Do you know how much I need to get milled off to get to 68cc?

Sales2@Texas-speed

iTrader: (5)

You'll mill about .010-.015" to net 68cc chambers on a stock LS3 head.

Samer

I totally agree with Matt.

Just measure your piston to deck clearance to make sure that its at zero. If your pistons are in the hole, you might need to mill your heads more to reach 11.5

matrixiskool

iTrader: (12)

Why might it not be at zero?

Sales2@Texas-speed

iTrader: (5)

When you have your machine work done, some blocks will need the deck surfaced decked more than others and some builders won't touch them at all even if they need it. That will affect the piston to deck height.

matrixiskool

iTrader: (12)

I talked to my machinist he told me he would check the mains, deck and everything when he goes to bore and hone it.