brandon5770

well heres the deal i have a lq4 6.0l with 317 aluminum heads?

question is how much can i mill/shave the heads for more compression and be safe?
I have a cam specs are- xr-288 hr
lift- in-580 ex-590
dur - in-288 ex-294
236-242@050
i think 112 lsa?
also got 7.4 comp pushrods and gmpp racing lifters patriot dual gold valve springs other than that thats it!
this is going in a 78 chevy luv rat rod/drag truck i want all the compression i can get also might run 150 nos i have later on oh and its carburated 750 holley with victor jr intake and headers

cws T/A

iTrader: (3)

You will need to measure your current p/v clearance [unmilled] and decide how much you can mill without compromising the p/v clearance . Minimum is .080'' Intake / .100'' exhaust .

You could swap the 317's for LS2 243's and gain quite a bit of compression without milling .

317 = 70-71cc

243 = 64-65cc

brandon5770

thanks for the reply this is my first post. I am kinda on a budget so different heads are out of the question at the moment lol. i have a friend that runs a machine shop who is gonna do the work on my heads.

whats the best/easiest way to measure piston to valve clearence? i already have heads off the motor?

the_merv

iTrader: (88)

You can use Clay or Putty..put it in the Cylinder and put the Head on, and turn the Engine over by hand. Then take the Head back off and see how far the Valves went down with that rotation.

brandon5770

ok then measure the putty?

djsanchez2

iTrader: (14)

Yes use a micrometer to measure the thickness of the putty. You can also use a tootsie roll still in the wrapper, easier to do because the tootsie is harder and the paper is wax lined. The thickness is your clearance.

the_merv

iTrader: (88)

^^Never thought of that one..lol

LS6 Silverado

iTrader: (27)

Stock lq4 pistons??

brandon5770

ok tootsie roll lol
yea stock lq4 pistons