Pushrod length?
Thread Starter
Teching In
Joined: Mar 2009
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From: Wheatfield, Indiana
Pushrod length? 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
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
Well, best thing to do is get you a pushrod length checker for you to set it up properly. Have teh heads been milled?
Thread Starter
Teching In
Joined: Mar 2009
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From: Wheatfield, Indiana
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
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
Shane
Last edited by XtraCajunSS; Jun 29, 2009 at 03:13 PM.
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
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.
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Teching In
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From: prescott az
Jim in Prescott --- 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.
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.
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
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
Shane
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.
I love the LS rocker set ups vs the LT1 rockers.
