Warhawk111

I got a 6.0L iron block, 243 patriot heads, stock ls1 rockers, and an after market cam. I was wondering what size pushrods i need for this thing. Its my first LS series motor build. Im using an MLS head gasket that has a thickness of .051. Anyone got an answer? Thanks

Gen414

iTrader: (38)

Well, best thing to do is get you a pushrod length checker for you to set it up properly. Have teh heads been milled?

Warhawk111

The heads are brand new patriots stage III with 59cc combustion chamber, i do not know if they have been milled, i do have a push rod checker but exactly what am i looking for as far as how the pushrod feels? I understadn stock lenght is 7.400 so i could imagen starting a little under that but how do i know when its the right length

Warhawk111

Can anyone tell me what im looking for when checking pushrod length?

XtraCajunSS

iTrader: (2)

Put a stock 7.400 pushrod in and get the lifter on the base circle of the cam. I use the EO/IC method (exhaust opening/intake closing.) Tighten the rocker down until you are at zero lash (all slack in the rocker is gone but the pushrod still spins freely.) Set your torque wrench to 22 lb./ft. and count the number of turns it takes to achieve full torque. You are looking for between 1 and 1 1/2 turns. 1 full turn is ~.047" so if you get 3/4 of a turn you need a .025" longer pushrod to get in range. If you get 2 turns, you'd need at least .025" shorter to get in range. These specs are with stock type lifters.

Shane

Gen414

iTrader: (38)

Also need to check for "sweep" of teh rocker across the tip of teh valve. Say you have a REAL long pushrod, and you rotate the motor, teh rocker arm will only "sweep" across the back half of the valve. NOt sure if I just confused you are helped you.

XtraCajunSS

iTrader: (2)

With stock rockers and those heads, his sweep should be fine. Not really necessary in this case.

Thanks,
Shane

Gen414

iTrader: (38)

Yeah, forgot he was running stock rockers, thats my bad

jim copland

From what I have been lead to believe, you want the lifter compressed between .030 & .060. and i don't think that the 1.5----2.0 turns on the adjuster nut is quite right [because of the rocker rario ] . The way I believe it should be done is with a dial indicator on the pushrod end of the rocker and when torquing the adjuster to the 22 lbs.you should be able to verify that you compress the lifter in that amount. If I am correct I think its going to be closer to 3/4 turn max, and when you accomplish this the sweep on the valve stem should also be correct. I hope someone there can confirm this, or point out my misunderstanding.

XtraCajunSS

iTrader: (2)

FWIW, I did this years ago. With a dial indicator setup on the pushrod end of a stock LS1 1.7 ratio rocker, 1 full turn of the bolt equals ~.047" of lifter preload. That is not accounting for bolt strech so once its taken into account, 1.25 turns is jsut about perfect on a stock LS1 lifter. Rocker sweep is only a factor in these engines when you are using non-stock components.

As long as we are discussing 1.7 stock GM rockers with an 8mm X 1.25 thread rocker bolt, these numbers are sound.

Hope this clears up any confusion. I explain this same thing over the phone about 5 times a day...

Shane

Warhawk111

Thanks guys it's helped a ton

rice8er

iTrader: (2)

so what size push rod do u need if u have 1 full turn?

rice8er

iTrader: (2)

anyone??

RyanSws6

iTrader: (72)

I'm also going to be doing this soon. I am going to try using a push rod checker. I've got no idea what range I'll be in. Cometic .030s and LS3 heads cut to 66ccs.

I love the LS rocker set ups vs the LT1 rockers.