Nasty N8

iTrader: (33)

Yes but way more costly. If you are unsure how to do it have a qualified shop install it.

Nate

Unaffliated Racing

iTrader: (15)

if you have anymore preload than the recomended .002"-.004" you "could" pop out the retaining clip in the lifter..thats why the preload is the way it is

LS171Malibu

dang... I just got the F1, comp r's, push-rod's (7.4) and the shop said nothing about preload... how do you check that? What shim material, and where does the shim go?

Nasty N8

iTrader: (33)

Shims could be as simple as washers under the pedistal.

Nate

LS1x2

iTrader: (11)

Another option is to use sheetmetal and just drill the holes in a strip to make one shim per side. This is what I did. Works great.

LS171Malibu

is it as simple as using one sheetmetal strip across... under the rocker fixture? How do you check for the preload?

DOC OTIS

iTrader: (9)

There is a really good write up on how to install Yella Terra rockers on ls1howto.com. In short (from what I gather anyway) is get both valves closed (zero lash) then tighten the rocker bolt down by hand as far as you can. Then get your torque wrench and set it too 22 ft pounds. Count how many revolutions u get till the bolt is torqued down. Each 1/4 turn is supposed to equate to about .010 to .012 in preload on the lifter. When I did mine I came up just short of a 1/4 turn so I am guessing I am somewhere between .006 .008 preload - hopefully that will be good enough. Like I said check out ls1howto.com there is alot of very good info on that site. Hope that helps

DOC OTIS

iTrader: (9)

oh and if your not using the Yella Terra rockers I am sure you would check the preload using the stock rockers (or any non adjustable bolt down rocker) the same way. That was probally obvious but I figured Id throw it in in case anyone was confused

Unaffliated Racing

iTrader: (15)

well..there is only one problem with your method..since you are doing it this way..your rockers are no longer torqed to spec..with means they could back off, causing problems and a lot of headaches

DOC OTIS

iTrader: (9)

Not sure I know what your talking about? If I torqued the bolts too 22 ft pounds how is that not torqued too spec? Please explain you lost me

LS171Malibu

so if I set the piston at tdc on the combustion stroke... and put plasti gauge between the rocker and pedistal... then tighten by hand untill the rocker makes contact to the pushrod and valve... remove rocker.. measure plasti gauge... that would be the preload? Then make a shim that would make the preload .002"-.004" for the comp r's? Does that make sense?

Nasty N8

iTrader: (33)

Comp`s will requier about 1/4 of a turn til tight from zero lash. Don`t make it that technical.

Nate

Unaffliated Racing

iTrader: (15)

No,...a 1/4 turn is too much preload..as I stated before if you have too much preload then you "could" pop the retaining clip out of the lifter

LS1x2

iTrader: (11)

You guys are funny. Arguing about this ****. You have non-adjustable rockers. You can only do so well with this. I did not use any special tools. I made different shims from sheetmetal and tried 3 of them out. Got it just rigt. Could tell by sound a feel. Revs tp 7500 no problem.

LS171Malibu

Well, tonight at work I made some strips out of 0.050 shim stock... the cool thing about this **** is it peels away like foil and I can make the shim as thin as needed. Hopefully I can use plasti gauge or a feeler gauge to determine the required thickness.

DanZ28

iTrader: (5)

Don't know what you plan on doing with plasti gauge or a feeler gauge, the pre-load is done at the lifter. In other words, your pre-loading the lifter (pushing down the plunger) by the amount of turns you make on the rocker bolt from "zero lash". You can only do this by counting turns or using a dial indicater with a stand and you only want to push the lifter plunger down .02-.04" on a Comp R lifter. Hope that helps!

Dan

LS171Malibu

I didn't even think of using a dial indicator... that is a great solution, and I have one. Thankyou!

LS171Malibu

BTW... did you mean .002"-.004" OR .020"-.040"?

Unaffliated Racing

iTrader: (15)

.002" - .004"