mrclean200518

iTrader: (89)

how do i use this ecactly wanna make sure im doing it right

vettenuts

iTrader: (4)

Each turn of the pushrod is 0.050". When fully closed, it is 6.800". This is pushrod "gauge length" so you can't measure it directly as the pushrod length is actually based on the length between the ball ends where the ball end measures 0.140" in diameter. Assuming you are using stock rockers or a non-adjustable rocker.

1. Open the adjustable pushrod to the same length as your stock pushrods
2. Close it down two turns
3. Put your rocker rail on the head
4. Make sure you cylinder (typically #1) is at top dead center on the firing stroke so both valves would be closed
5. Put the pushrod in place on the intake valve and make sure it is in the lifter cup
6. Install the rocker and snug down the bolt (don't need to torque, just make sure it is snug)
7. Lift rocker tip up and down, if it "ticks" the pushrod is too short. If you can't easily move the rocker the pushrod is too long.
8. You can try and adjust the pushrod in place buy my fingers are too fat so I end up pulling the rocker and adjusting the pushrod length. Go either shorter or longer 1/2 turn and try again.
9. You are trying to get to the point where the lifter doesn't "tick tick" with the pushrod in place nor is the rocker snug. When you get the pushrod length such that you just barely get rid of the "tick tick", you have found "zero lash".
10. When you have found zero lash, carefully remove the rocker and pushrod without rotating the pushrod.
11. Tighten the pushrod until it is fully closed counting the turns as you go.

To figure out your pushrod length you do the following. Lets assume it took 10-1/2 turns to close the pushrod down to its shortest length after you reached zero lash. Each turn is 0.050".

Your length is then: 6.800" (fully closed length) + 10.5 X 0.050" (number of turns times the length change per turn) = pushrod length minus preload. So for this case:

6.800 +10.5 X 0.050 = 7.325"

This is the length you measured to zero lash without any lifter preload. Now lets say you want to have 0.075" lifter preload, you add that to the measured number and you end up with 7.400" pushrods.

Now repeat for the exhaust valve to verify the length. If you have something like Yella Terra's, it is the same procedure but you must snug down the rocker pair rather than the single rocker.

mrclean200518

iTrader: (89)

thank u very much man, i am totally lost and that just made it crystal clear as to what i am doing i dident understand the preload. im running oe style comp cam lifters, with 04 zo6 cam stock lifters and 04 ls6 heads i got from gmmp. i got it all together and i have a ticking it is coming from my top end so im assuming my stock length ones are to short

vettenuts

iTrader: (4)

Also check your rockers and make sure none of them lost their needle bearings while you have the covers off.

brad8266

iTrader: (23)

Yup exactly like he explained it.

mrclean200518

iTrader: (89)

i got it guys, i went out and took the cover off and when i take one of the rocker arms off and reinstall it its tight but after a few minutes it seems to loosen up and dont have any lash in it i can move the arm from side to side but after i turn the motor over and get it back to tdc its loose again . shoud my rocker arms have any play in them . i used the checker and im getting a 7.450 length and it seems to stay tight

brad8266

iTrader: (23)

The looseness may be from the lifters giving in. Dont turn the motor over with the checker in place.

mrclean200518

iTrader: (89)

do i want it to do that though

brad8266

iTrader: (23)

You dont want to turn the motor over so as to put "give" in the lifters. Do it like vette said, just get to TDC when both valves are closed and put the checker in place and tighen down the rocker nut a little bit. It is normal for the rocker to have a slight looseness in it though, that is the slop in the rockers bearing tolerances.

mrclean200518

iTrader: (89)

ok so if i get this right i want the checker to be just snug and not to push the lifter down , then i add that on as pre load , but how much preload should there be because mine checks out at like 7.400 like it dont have preload but when i put the 7.450 in its nice and tight now play

vettenuts

iTrader: (4)

The pushrod should be just barely touching the lifter cup and the rocker. It sounds like you are too tight. Approach the measurement from being too loose then gradually lengthen it. If you have a very slight "tick tick" in your measurement you are better off than too tight as the pushrods come in fixed lengths so a few thousandths won't make a huge difference. This is a feel thing. It sounds like you are depressing the cup in the lifter. Also, make sure you are at TDC. Once the intake closes bring the piston to the top. Don't move the motor once you are at TDC and don't use the adjustable pushrod when turning over the motor as it can't take the forces of the valve spring.

mrclean200518

iTrader: (89)

so when i adjust the pusrod should there be any movement in the lifter should i be able to take the rocker and push back and forth and the lifter give

E2ndgencamaroN

So are you just measuring zero lash with the cylinder at TDC and the rocker torque? Then once you finally get the noise out of the rocker you pull out the push rod length checker and turn it till it is that smallest it can be length wise and count the turns? With that said you then multiple the the number of turns by .05 to get the adjustment you needed. Then add that to the length of the push rod length checker when it is at its shortest measurement. Is all this correct? Then do you just add the lifter preload to that measurement? How do you know what this measurement is? Also how off can your measurement be from a push rod length that you order whats a good rule of thumb?

Thanks

Burken01

iTrader: (88)

You're over thinking it, post #2 explains it step by step from one of the best...

find zero lash with the checker and keep note where the mark is on the PR checker.. unbolt the rocker arm and gently pull the PR checker out without disturbing the marks on them.. then just count the turns it takes to get back to "fully closed"

so lets say it was 10 turns to "fully closed" so that's 10x .050 = 0.500

PR checker is 6.800, add .0500 to it and you get 7.300

then add the desired preload to that, each lifter has its desired preload range.. ls7 lifters are usually setup between .050-.080 preload

so take 7.300 + .050 (preload) = 7.350 < this is the PR length you would order

E2ndgencamaroN

Right... so then when your checking do you torque the rocker arm then try to find zero lash then disassemble and measure?

Burken01

iTrader: (88)

yes I torque it, usually takes a few attempts and then you'll have the measurement.

E2ndgencamaroN

okay thanks