grantpo

I know this has most likely been discussed but couldn't find a definite answer with the google machine.

2006 LM7 5.3 with dished pistons, if I slap on a set of 799's that are milled .020 already what will my compression ratio be?

And what would it be if I swapped in a set of 5.3 flat top pistons from a Gen 4 motor with those same .020 milled 799s.

This is in a Jeep wrangler and would rather not have to rebuild the short block on a great running motor, but don't want to loose to much compression. Seems like most people say you have to mill these heads .030 to return to stock C/R.

omc8

iTrader: (7)

Well 243 with a ..020 mill will be approx 62 cc if nothing was done to the chamber . So you may lose just a bit cr. Flat tops with stock unmilled 243 yields 9.9:1 So figure it from there.

01ssreda4

iTrader: (96)

Unless youre going for all out power just put it together and dont worry too much about it.

Kawabuggy

iTrader: (1)

You can also run the Cometic thinner head gaskets at .041" and gain a little bit of the lost compression back. Depending on PTV clearance with the cam you are using of course.

grantpo

Thanks for the replies yall. Yeah I'm leaning to just keeping the short block stock with the dished pistons and sell the flat tops, just curious where I'll be on C/R.

This is the cam I got EPS cam 210/212 .604"/.604" 112 LSA

Also already have LS1 head gaskets

Little more details on the heads 799s rebuilt with Brain Tooley dual springs, milled .020, and 3 angle valve job.

NNBS intake, 87mm TB, and X-Link

omc8

iTrader: (7)

Pop a valve out and take a look see if there was a bowl blend done .If not these can see good gains from this. Let us know how that nnbs intake works with the xlink.

JoeNova

dished 5.3 with LS1 head gaskets and 799 heads is around 9:1. You'll still be less than the stock 9.49:1 even with a .020 mill.