TripleWhite96

iTrader: (29)

Casting number 317 6.0L LQ4 Truck Head
Decked to 68 cc chamber
Valve Job'd
New LS2 Intake and Exhaust Valves
New Seals
New LS6 Valve springs Good to 0.570 " Lift

I was wondering what you guys think of these, they are 68cc so i'm guessing on stock bottom end thats around 9:5.1? I was thinking of picking these up and run a z06 cam(if I can find one) and ls6 intake with no EGR. Stock 317 heads are 72cc correct? Would I be better off looking for 70-72cc? i'll be running 7lbs until the bottomend/tranny are done being built. I'd run the car with 5lbs until the motor was built but I only have junky 853 heads and I figured I might as well just finish the top end and run 7lbs and be able to enjoy driving it to work everyday until everything else is done. Just looking for some advice - Thanks guys

code4

iTrader: (30)

I'd prob just keep the stock heads until I built the bottom end. Then I would get heads spec'd for the exact compression you want.

You didn't say what the 317's cost. And the springs on them are not stout enough for boost so you'll have that expense anyway.

TripleWhite96

iTrader: (29)

The cost is $500, i'm sorry looks like I forgot to put that in the post. Do the 853 heads support 7lbs reliably with a good tune? If not i'd have to get a 5lb spring for the WG and run of the gate..i'm guessing I would do the same with the spring for the BOV? On the 853 heads though I could not find any threads talking about them - everyone just swaps to 317s right off the bat. Fuel will be 2 255 pumps, hobbs switch with 60lb injectors stock rails and lines.

TripleWhite96

iTrader: (29)

Also in terms of the springs, a sponser here is selling 6 of them or so - they will change them out if need be

ls1290

iTrader: (20)

853 heads have 66.67cc chambers, so the milled 317 are not going to buy you much as far as lowering the compression level. But since the 317 have had a valve job and have better exhaust runners than the 853, they will flow a little better. If you are only going to run 5 to 7 pounds of boost, the 853 heads will work just fine as the 317 will not be a huge gain. I would save the $500 for the tranny first and then the bottom even.

TripleWhite96

iTrader: (29)

Sounds good - I really didn't want to tear into the heads of the car while im building a forged LQ9 on the side in the near future - $500 toward the TH400 with transbrake sounds better Just wasn't sure if anyone has ran stock 853 heads with 7lbs with a daily driven car. Everyone makes it seem if they aren't 317 heads and FI cam or Z06 cam the car is pretty much going to blow. I don't abuse my car and 7lbs would be the highest I go until the motor is done.

Pro Stock John

iTrader: (34)

Yeah I'd wait until you do a build and do some thicker deck aftermarket heads like AFR's or TFS's.

TripleWhite96

iTrader: (29)

Thanks so much guys I appreciate your help and information FI section rocks! I'll do just that. Motor will stay complete stock with my 853's on 7lbs other than twin pumps, 60lb injectors and MSD wires with TR6s :p I have to make a build thread soon and introduce both of my prides!

98Z28MASS

iTrader: (6)

I would say you might still want to swap out the valvesprings to at least some comp 918springs if not patriot duals as im not sure if those stock springs are up to the task? Otherwise I agree with everyone else and stay with the stock 853 heads until you have the forged shortblock and go with a good head (AFR and TFS come to mind)

L3THAL_Z28

iTrader: (5)

just build the bottom end before u start throwing other stuff into the mix