Tin Indian

I don't know the factory spec on LS1 lifter preload, but I have heard that the rocker bolt will turn approx 2 turns from when at zero preload until 22 LB FT torque is applied. This of course is when the lifter is on the back side of the lobe (heal of lobe) (valve most closed position)

Can anyone confirm this?

Thanks,
Ron

Nickn20

eh? just TQ them to 22 ft/lbss crank the motor over a few times and re TQ them all and you are good to go, with stock rocker arms of course.

Tin Indian

Nick....

I can understand what you are saying, but here is the problem;

This is not my car, but someone elses...

This guy has installed valves that are longer than stock (2002 LS6 hollow sodium filled valves)

He has an aftermarket cam (which has a smaller base circle than stock)

Heads are milled 55 thousands

He is using stock GM hyd. lifters

All this **** has made it very difficult to determine what length pushrods to use.

All he is trying to figure out is his correct lifter preload.

Lets put it this way; .... Take a bone stock LS1.
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1. The valve we are checking will be placed at TDC. (valve will be fully closed) I other words, It's lifter will be located at the backside of the lobe heal) (opposite of the lobe)

2. Loosen the bolt on that rocker arm till the pushrod is loose.

3. Now, tighten the rocker arm bolt until the pushrod starts to [not] spin when turned by your finger. This will be "zero lash".

3. Mark the bolt head with a magic marker

4. Then tighten it till you get 22 LB FT torque on the bolt

5. Look and see how many turns it took to tighten up

My guess is 2 turns. If that is correct, this guy can then install the correct lenght pushrods to get the correct lifter preload (2 turns -- if that is correct)

Thats what this question is all about....

Thanks,
Ron
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<small>[ October 15, 2002, 07:41 AM: Message edited by: Kimchee and Rice ]</small>

JPR

2.2 turns down is factory lifter pre-load stab depth, anything + 2.5 requires a shorter push rod. Tq to 22 ft lbs <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> .

Joe.

<small>[ October 15, 2002, 09:08 AM: Message edited by: JPR ]</small>

Tin Indian

Thanks alot Joe <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Redline-Motorsports

iTrader: (3)

Lifter preload should be around .030"-.040". Any more then that and you could cause the lifter not to feed oil to the upper valvetrain.

Lunati, Isky etc. all make pushrod checkers. You can also make one by cutting a stock pushrod, thread is 1/4 20 and install a threaded rod. .055" is quite a bit and will most likely need a smaller pushrod. Make sure you check the travel of the rocker tip on the valve stem and to check clearance at retainers.