bluebommer07

iTrader: (7)

ok i will be building a lq4 with 317 heads, i know everyone says go 243 but these are free and for me free is anyway, i will be running a 222/226 eps cam i want to mill the 317s down a little to up compression, my question is how much can i go before i have ptv issues and have to change push rods and any thing else that might come into play. also i want to still be able to run 87 oct if possible or next grade up

autogeek23

iTrader: (13)

You want to up compression but use 87 or the next grade up. I'm not to sure about that

bluebommer07

iTrader: (7)

im new to this that y i ask

Blk98Vert

iTrader: (2)

That's counterproductive. You can run 87 if you don't mill the heads. Generally milling .030 is the accepted amount. PTV shouldn't be an issue with that cam.

bluebommer07

iTrader: (7)

what size gasket should i run also?

conan

iTrader: (5)

You'll want to run the 6.0l gaskets to clear the 72cc combustion chambers in the 317 heads. GM make a MLS gasket or cometic. I run a 4.030 cometic on my 5.7L/317's.

98BLOWNZ28

iTrader: (10)

Not sure why 87, lol, but I'm sure you could run it if fine if you dont get on it. Lol. Think that kinda defeats the point though?

sepsis

iTrader: (7)

Premium gas isn't that much more expensive ffs. On a fill up, you're gettin maybe 1 gallon less with premium for the same amount of cash. If you can't afford premium gas, you should drive something more economical.

bww3588

iTrader: (49)

Nothing wrong with 317's, they are the Same essentially as the 243, Just with a larger combustion chamber. A good mill and a thinner than stock gasket will bring you right on par with a 243 head.

And I agree, generally premium gas is 20 cents more a gallon than regular. On a typical 10 ish gallon fill up, you Will spend 2 bucks more going with premium, and your car will thank you in the end.

bluebommer07

iTrader: (7)

That's my question what size basket to run and how much to mill to get me right at the 243

bww3588

iTrader: (49)

It's tough...

.0065 mill is roughly 1 cc. To go from 72 cc's, to 63 ish, you Will have to take around .060 off it, which is a lot.

bluebommer07

iTrader: (7)

I was told .40 is the most which would be around 65-67 I think which to bad.

Marc 85Z28

iTrader: (8)

Just sell the 317s and buy some 243 or 799 heads. The money you save on the more expensive gaskets and milling will help offset the cost differential. Milling that much from the 317s will hurt flow and PTV clearance.

PowellSixO

iTrader: (1)

Sorry to hi jack, but I'm thinking of sending my 317's down to be milled to bump compression a little. If I have the machine shop take off .040", will that cause any intake fitment issues?