I have a 2006 rcsb z71 with an LM7 and 706 heads. I found a set of LME cnc ported 243's milled .024 with BTR .660 platinum springs with titanium retainers. I'm trying to see what pistons I have without removing my current heads. Also wondering if these heads would be good for my application. Going to go on a turbo 5.3 and looking to swap heads from the 706's. My research time is very limited with a new son and long hours. I know there is a lot of knowledge on here and any input would be appreciated.

 

You should have the standard dished 5.3 pistons..

 

Thanks, does anyone know what compression ratio these heads would yield with LS9 head gaskets? Combustion chambers are 65cc.

 

With 65cc you are going to be around 9:1 compression ratio.

If this is going to stay in NA you can have the heads milled to bump that back up.

Factory 706/862 heads are around 61cc and around 9.5:1 compression ratio.

 

Theres a set of L33 pistons for sale somewhere on here (just saw them this morning) that would bump compression up too...

 

https://www.performancetrucks.net/fo...irrors-542403/

 

I've seen flat top Pistons in the 5.3 motors... I had a 06 and a 07 iron 5.3 that had flat tops.... And my 07 Tahoe 5.3 is factory flat top Pistons.... I believe they started using the flat tops in 5.3 around 2005ish maybe? Not sure if it was for all the motors or just H.O. Motors?

 

HO and gen iv typically have flat tops

 

Are the combustion chambers on the 243's 59-60cc?

 

Carefull about the info you provide. See below


Yes Gen VI applications had the flat tops. Those are 58X motors not the Gen3 24X motors.

Only 24x with flat tops was L33

No around 64-65cc on all 243/799 castings.