redbird555

iTrader: (14)

Ok guys so heres the deal my ls6 scored a cylinder so I pickedup a new l99 shorblock that I'm currently converting to ls3 specs. Eventually i'll add a small cam but right now I just need the car running. Stock compression on the l99 iis 10.4 and stock compression on the ls3 is 10.7.

I want to bring the l99 up to at least ls3 compression maybe a tad higher. I already have ls3 head gaskets I was planning on using. I know I could go with cometics but i hear a lot of instances about them leaking and I just cant take that chance. Basically where would a.02 mill put me with the l99 pistons and rectangular heads?

redbird555

iTrader: (14)

bummp anyone

CAMSTER

iTrader: (10)

Hey neighbor never heard of Cometic head gaskets leaking we reuse them still no leaks.

About how much to mill off the ls3 heads depends on how much compression you want to add, but this you can figure out;

for every 5.880 thousands you mill off you will increase 1/10 of a point of compression which is to say if you mill .060 you will gain a full point of compression.

Now to address your question on max you can mill off an ls3 head, I have done .140 or from 69 cc down to 45cc combustion chamber, or from 10.7 compression to 13.5 after fly cutting the stock pistons.

dogsballs

Above is spot on. I've gone 125 thou on my heads

carbuff

iTrader: (8)

With that much mill, are you guys angle milling both the deck surface and the intake surface in order to keep the intake port entrance in the correct place and to allow the correct intake seal?

redbird555

iTrader: (14)

thanks guys I have an l99 block which is the same thing as an ls3 but with valve reliefs which lowers compression to 10.4 from 10.7. I just wanted to get stock compression lol so I went with cometic .040 gaskets which by the calc should get me right to 10.69:1 and reduce quench to .032-.033

dogsballs

Previous engine with 100thou removed, the plastic manifold bent a little as you snug down the bolts, then vic junior also bent a feaction and fit unmodified.

Haven't tried my new 125thou combo yet. Will be shortly