53bowtie

iTrader: (6)

The flow I think was determined to be the same between the 243's and 317's being that they have the same size valves and all. The only difference is the combustion chamber with the 317's having a 71 or 72cc chamber I believe and the 243's haveing a 64.45cc chamber. The only advantage I have seen for the 243's over the 317's is the ability for a higher compression ratio since I think the lowest you can get the 317's is around 67cc or so.

I would also like to know the price for a cnc port job from wcch.

GMCtrk

iTrader: (27)

You should be able to take 317s down to 64 or 65cc's with a .040 shave. But why, that is the question. 243 is already that and no PTV or intake sealing issues

BigCountryx

iTrader: (3)

A little bit of a thread Jack, but I've got a budy with an LQ4 and has a set of 862 truck heads, I've heard they are the same as a 243 with a little smaller chamber. If this is so, he's looking at a little over 11 :1 would this be a good combo and would it be alright on 93 oct?

GMCtrk

iTrader: (27)

The 862's are very similar to the 241 heads with smaller valves. Zippy put those heads on his lq4 tahoe, but he had the 2" valves put in. It works very well.

ramdaspadhye

iTrader: (3)

Don't you have the 317's? Just have them milled down .040 if you're on a budget, should give you around a 64cc chamber and you shouldn't run into PTV clearance issues unless you're running a high duration cam with a lot of lift. Will give you low 10.x:1 compression depending on what head gasket you're using. Guy on LS1tech can hand port them to give around 29x around 600 lift on each runner, Bo White I believe is his name.