317 Heads?

Reply Subscribe

Thread Tools

Search this Thread

Mar 19, 2007 | 07:21 PM

sugarwolf

Thread Starter

Pro

Joined: Nov 2004

Posts: 601

Likes: 1

From: Wa

317 Heads?

I am picking up a set of 317 6.0L Heads or called the LQ9-LQ4 heads for cheap and having them milled .030 to bring the cc's to the same as the LS1 heads. Should i have them ported too? I am putting them on a 98 MN6 coupe and adding the TR224 cam. I have noticed there isn't too much about the 6.0L heads on this board. There the same as the 243 heads but with bigger combustion chambers 72cc vs 64cc 243 heads. Just thinking should i have them ported or throw them on as-is?

Mar 19, 2007 | 08:22 PM

TheCartel

Melting Slicks

Joined: May 2004

Posts: 2,118

Likes: 12

From: 918 OK

I know forced induction guys use them to lower compression. Other than that, I can't tell you anymore.

Mar 19, 2007 | 11:20 PM

sugarwolf

Thread Starter

Pro

Joined: Nov 2004

Posts: 601

Likes: 1

From: Wa

Well i don't see much on here about them even for forced induction. I can get a set for 150 bucks and spend 50 bucks on getting them milled .030 to bring cc's to 67.66 same as the Ls1's and save 300 bucks not getting 243 heads and they flow the same.

Mar 20, 2007 | 09:33 AM

Billdog350

Drifting

Joined: Dec 2005

Posts: 1,720

Likes: 3

From: East Hampton CT

I think there might be some valve clearance issues because the 317's have a bigger combustion chamber, not just a thicker deck. When you deck the heads you bring the valves closer to the pistons. It will depend on which cam you go with, but I believe that 243's are better on the 347 motor. There was also some talk of squash area at the top of the piston with the 317's not being as efficient at the 243's due to different combustion chamber (for the larger bore 6.0l). Someone with more experience can confirm.

Mar 20, 2007 | 09:44 AM

kromberg

Le Mans Master

Joined: Jan 2001

Posts: 5,785

Likes: 6

From: Lafayette Colorado

For how well the L92 heads flow out of the box, I do not see any reason to have a set of LS1, LS6, or LQ4 ported. The L92 heads flow better and are cheaper than any ported set of heads I know of.

Keith