my friend has a 06 cammed 5.3, with stock 706 heads... (918's springs)

what will his compression be with port/polish, and .030milled and stock valves?? some body told him his compression now is 9:5 and with the above work done on the heads it should go to 10:1

is this true?? thanks for the help...

 

It depends if the port/polish work makes changes to the combustion chamber. With the chamber work on my WCCH Stage I heads the chamber size went from 61 to 65cc. WCCH then milled them .045 which brought the chamber size down to 58.8cc. With stock gaskets, I'm at 9.85:1 SCR. If I used .045 thick head gaskets like my original plan I would have been at 10:1.

 

so why didnt you go with the 10:1 setup??

 

It's a long story. My truck is a DD, which means that I only have from Friday night to Sunday to get it torn down and back up running.

I had bought 3.910 bore .045 Cometics to use. The instructions said to install them dry as opposed to all the people on tech that said to use the copper gasket spray with them to help with sealing.

Tore it apart and put it back together from Friday night to Sunday at 10AM. I thought I was golden. Started up the truck, everything is great. About 5 minutes into it idling, I noticed coolant seeping from the pass side head . Tore it apart and retorqued it, still leaked. Wouldn't hold under a pressure test at all.

Had a decision to make, try to get new GM gaskets on a Sunday afternoon, or try the Cometic again with the copper spray. Then read that the gasket has to air dry for 24hrs before using the gasket spray . So I called the parts guy from the local Chevy dealer (family friend) at his house, he says he has a set in stock so I met him there and bought new gaskets.

Put it back together a 3rd time, and started it up at 12:00 Monday morning and took it for a test drive at 12:30AM. All was fine, and I called in sick to work. I traded the Cometics for a set of 28.8# injectors for my LS6 intake project.