way2much_01

iTrader: (6)

hello I gotta a 05 avalanche 5.3 and I bought some 243 casting heads off a vette and I read from a tech book that they should be milled at least 0.030 due to lost hp and compression and then I heard that it didn't matter and someone told me today they should be milled I was just wondering if anyone has had this situation or if you know anything about this?

SSSBLKOUT

pm richard@wcch, he'll know the exact specs.

I know that 243s were 10.9:1, or something close to that. if you take of the 5.3 heads (which are at 9.5:1, i think) I still think you'll be close on the CR.

nighthawk08

243's have 65 cc chambers and 5.3's have 61 cc chambers. You'll need to mill quite a bit to even get back to stock compression.

ZR1 DREAMING

iTrader: (28)

Right, the 243s were origionally for a 4.00" bore. Bolting them to your 5.3 will drop your CR significantly.

Tootall

iTrader: (79)

I have a friend that put 243s on a cammed 5.3 . . . he had the heads milled .030, and so far is loving his setup . . . . no times yet.

nighthawk08

you can get ported 5.3's for like $1k now. These will easily outflow 243's and you could have them milled at the same time and run like 10+:1 compression. I just dont see the advantage of running 243's on a stock piston 5.3.

Tootall

iTrader: (79)

243's . . . $400 at the worst, milling, $100-$130 at the most . . . so for 500 to 600 you can have some great flowing heads.

way2much_01

iTrader: (6)

so I would be better of keepin my stock heads and changing the rocker arms and springs and things basically?

sevans327

iTrader: (2)

what about getting l33 heads? There based on the z06 heads but made for the 5.3
Shawn

trever1t

iTrader: (14)

799's......I wonder what the chamber size is on them? The L33 has flat top pistons to = 9.9 to 1 CR.