man2004

iTrader: (1)

I was looking for ported LS6 heads (for an LS1 moderate cam, NA) when I came across a set of hand ported 317 heads on eBay. The price is right. But, I am reluctant since I have read that the 317 is more suited for a boosted application than my application (naturally aspirated) due to the fact that the chamber size on the 317 is larger than the 243. Is it better to wait for a set of 243's to come along?

Sales4@Texas-Speed

iTrader: (4)

I would wait on the LS6 heads because a drop in compression would not work well for an N/A setup. 317's head flow great but if you kill compression your low end power will suffer. 317s can be milled to the same chamber size as 243s but your cam probably wouldn't clear the pistons anymore. Wait for the 243s and get them ported and you would be better off IMO.

JPH

iTrader: (2)

Great answer, was thinking the samething along these lines.

lemons12

iTrader: (71)

I have ported/milled 317s on my car with a 226/228 .588 114 cam... I don't know what they flow but they have to be decent, full weight car and I run bottom, bottom 7s @ 95+mph.
I would guess mine flow better than a PRC stg 1 ls6 head (I had those on my last Ms4 car).

Isolde

iTrader: (4)

Milled 317s don't equal stock 243s, because the 243s have more efficient chambers. This has been tested and proven, though I don't have the link handy.
Plus who knows who did the hand porting, or how good it is?
Let these heads go.

CHADMACK282

799 heads from a 5.3 are the same as the 243. Only difference is the 243 have hollow valve stems. Wait for a set of 243 0r 799.

oange ss

iTrader: (50)

not all 243 heads have hollow stem valves

lemons12

iTrader: (71)

I don't know what my heads flow but I would put money that if i switched to a stg 1 ls6 ptc head I would run slower.