ChucksZ06

iTrader: (9)

I am building my first ls engine and was wondering about piston to deck clearance. I have an ls2 block, 4" eagle crank and rods, Mahle pistons. My pistons are about .005 in the hole rather than .006 to .008 out of the hole. My question is: Is it common to have to mill the block deck with aftermarket rotating assembles in order to get the piston ht at .008 out. Thanks.

jrp

iTrader: (16)

GM's deck height tolerances are 9.235 to 9.245, not all engines are gonna be .008 out the hole. i've seen the gammit of .002 to .010 on OEM short blocks. at only .005 in the hole i wouldnt worry about it, though you can mill the deck if you'd like.

FWIW my forged rotating assemby comes .010 out the deck in my 346.

Jason99T/A

iTrader: (21)

Chuck,

What is the compression height on your pistons?

jrp

iTrader: (16)

if it was anything other then ~1.120 assuming a 6.125 rod wouldnt they stick alot further out of the deck?

ChucksZ06

iTrader: (9)

Thanks for the replys. I am either going to have the decks milled or get a thin cometic head gasket. The pistons are dished -12 cc mahle and with 64 cc chambers I have to keep the quench down to stay above 10.5 cr. If I had it to do over again I would have went with 72 cc and flat top pistons. The machine shop was impressed with the ls2 block...he said it was the only time he has not had measureable bore distortion when the torque plate was torqued down. This block has all the same length studs. I wonder if that pulls more evenly than the longer and shorter bolts in the earlier blocks? Thanks again for the help.