milling 317 heads
04-07-2007, 06:03 PM
#1
Teching In
Thread Starter
Join Date: Nov 2006
Posts: 46
Likes: 0
Received 0 Likes
on
0 Posts
milling 317 heads
Yes, I've used the search and have read just about every thread on the subject. Like most issues there are varying ideas. It has been awhile since the subject has come up so I'm tossing it out again looking for feedback from those of you who have done it. I'm thinking of .040 mill with factory mls gaskets, maybe .054 thickness I'm not positive. Should end up losing almost 7cc and raising compression to 10.25:1. Has anyone ran this combo on a lq4? Thanks
04-07-2007, 09:14 PM
#4
LS1 Tech Veteran
iTrader: (1)
Join Date: Oct 2003
Location: Wichita, Ks
Posts: 1,172
Likes: 0
Received 0 Likes
on
0 Posts
atom,
If you are going to use the truck as a daily driver and want to improve performance, I would only mill the heads .005" or so for flatness, get a good three angle valve job, and pocket port the bowls and smooth the short side radius on the heads. Then I'd add a mild cam like a 212/218 plus add better springs (like Comp 915 or 918 beehives), plus new valve seals and hardened pushrods. Have the PCM tuned for that cam and see where you want to go next. A good tune is extremely important. The tune can set your shift points and firmness in addition to getting the VE table right for your cam and heads. Power Enrichment is also very poorly set up on the trucks compared to the F and Y body LS1 cars.This way, you can get a significant boost and run 87 Octane. The extra compression will only give you about 20 to 25 HP and about the same in torque plus you will have to run 91 Octane. You can gain more performance with the steps that I've mentioned and run regular gas.
These are my suggestions for what it's worth.
Good luck with the mods and enjoy your truck.
Steve
If you are going to use the truck as a daily driver and want to improve performance, I would only mill the heads .005" or so for flatness, get a good three angle valve job, and pocket port the bowls and smooth the short side radius on the heads. Then I'd add a mild cam like a 212/218 plus add better springs (like Comp 915 or 918 beehives), plus new valve seals and hardened pushrods. Have the PCM tuned for that cam and see where you want to go next. A good tune is extremely important. The tune can set your shift points and firmness in addition to getting the VE table right for your cam and heads. Power Enrichment is also very poorly set up on the trucks compared to the F and Y body LS1 cars.This way, you can get a significant boost and run 87 Octane. The extra compression will only give you about 20 to 25 HP and about the same in torque plus you will have to run 91 Octane. You can gain more performance with the steps that I've mentioned and run regular gas.
These are my suggestions for what it's worth.
Good luck with the mods and enjoy your truck.
Steve
04-08-2007, 01:03 AM
#5
Baltimore Whore
iTrader: (95)
Join Date: Apr 2004
Location: In a van DOWN BY THE RIVER
Posts: 16,820
Likes: 0
Received 2 Likes
on
2 Posts
umm .40 is alot, you may run into intake fitment probs with it. I am not 100% but maybe, I went 25k on mine more peeps might chime in, I think a few went more then that so they might chime in on this...
Thread
Thread Starter
Forum
Replies
Last Post
GrooveCityZ71
GM Engine & Exhaust Performance
7
08-31-2015 12:05 PM
