RockCrawler95

I am new to this forum so please have some patience with me. I have just purchased a LQ4 out of a 2007 “Classic” 2500. Tore motor down last night everything looks good upon visual inspection. This motor is going into my rock crawler so building a motor that makes tons of power at 3K rpm and up is not suited well for my application. I have done a lot of reading and talked to some of the vendors on this forum. Should I mill my 317 heads down or just put L92 heads on motor? Keeping in mind I want good power but through a wide rpm band. I plan to keep the truck intake and my pistons are already fly-cut from factory.

MJC

3pedals

iTrader: (3)

mill the 317's

MPFD

iTrader: (5)

second that...

1lejohn

iTrader: (9)

The 317's are big chamber heads based of the LS6's. Like posted above they would be easier way to go for sure. The 02 LS6 cam picks these engines up a bunch for cheap reliable power. If you don't plan on running a custom grind.

KCS

iTrader: (20)

Between 317's and L92's, I'd go with the 317's.

3pedals

iTrader: (3)

I personally love my L92 heads, but unless you want to rev the **** outta your combo the 317's are just as good

intenseblue

iTrader: (1)

317s and stock cam

R6cowboy

iTrader: (3)

Mill the 317's for sure. Those should be more likely to have better torque and power down low.

MPFD

iTrader: (5)

A 6 liter with High compression and a 212/218 low lift is an AWESOME torque motor for 4wd trucks. Especially if your not bench racing, and actually want useable power.

RockCrawler95

how much do I mill off the 317 heads? also how much of a problem will I have with milled heads and a stock intake? will I have leaking problems?

MPFD

iTrader: (5)

Depends on the cam? If I was gonna mill them and run a low lift cam, .040"-.050", if the intake doesn't fit you just take few thou off the cathedral side. If you want a cam with more lift, you may wanna mill less... .050" mill with a .040" gasket on a stock lq4 short block should put you around 10.8 compression. I wouldn't want much more then that if you plan on going to Colorado climbing..

3pedals

iTrader: (3)

Lift doesn't matter with respect to p to v clearence, LSA and the icl matters more.
Regardless, a .030-.040" cut is doable without upsetting the intake port alignment. You will still need to check P to V clearence no matter what, but the smaller cams like 220/224 will be fine.

Sales4@Texas-Speed

iTrader: (4)

For good power throughout the power band I would do the 317s. The L92s have too big of a runner and valve to promote good low end power, especially if you can't get good compression. Small cam with good compression is a great recipe for a broad usable powerband.

garygnu

mill the 317 ,you can retain the stock rockers .look at comp cam 54-455-11 or 54-408-11 for torque .look at comp cam quest 6 to may be find a cam you like.

RockCrawler95

Ok, i will mill the heads. Afer do much reading i still dont know how much is safe without having intake manifold leaking problems. Any advice

MPFD

iTrader: (5)

It won't leak, that's BS. The intake will either fit or it won't. If it doesn't you just need to take about 10-15 thou off the intake sides of the heads that will put it back in alignment. I've seen guys that were buying pistons take over .060" of l92's...

An lq4 with a 212/218 .521 .520 114lsa would work fine with cheap Yellow LS6 springs. It would clear a a .040" mill and a .040" gasket easily. It will make a metric butt ton of torque up to 6000 rpm and be crisp and powerful right off idle. I'd run a truck intake for even more torque.

My stock bottom lq4 with 243's, truck intake and a patriot cam made 487 ft/lbs of torque with a 3600 yank and a 3.73 gear at the rear wheels...

RockCrawler95

^ thanks for the great info.