smokeshow

iTrader: (16)

You could always do the 'spin the pushrod' trick to see when you're at zero lash and then see how many turns it takes until the rocker bolt is torqued. At least that way you'll have some idea of how much preload you're running/need to run.

budhayes3

iTrader: (19)

There ya go

I understand that you need the right pushrod the first time around, but your truck will be down longer if you take out a new set of lifters. The stock pushrods are 7.38, most guys with stock heads run 7.4 when swapping in an aftermarket cam on a pre-DOD GENIII, with no problems. There are pics floating around here that show the LS7 lifter cups to be taller than the original GENIII factory lifters, which has to be factored in. Cam base circle also has to be factored in. If the heads are milled, that needs to be factored in. If it were me, I'd buy the pushrod length checker, and a few sets of pushrods that are in the spectrum of possible correct lengths, then use the ones that fit and send the others back...or you can play roulette with what has worked for someone else, or someone else's buddy on the net...

Ferocity02

iTrader: (59)

I have a set of LS7 lifters sitting next to me, and yes the cup does sit up a little higher. I think I'll order some 7.350's and see if they or the stock 7.38's work better.

max1

iTrader: (12)

im doing the swap also...

i also went with ls7 lifters- but my heads are mill 0.30
i got my pushrod checker, but how exactly do you check for the correct lenght...

supercharged680

iTrader: (1)

LS7 lifters part numbers please

budhayes3

iTrader: (19)

Here ya go, 12499225, $121.95 for a set of 16 from SDPC (sponsor)

http://www.sdpc2000.com/details/gm-p...parts/12499225

Preston129

iTrader: (3)

Ideally you should have a dial indicator fixed to the pushrod side of the rocker arm, then just pick different lengths on the adjustable pushrod and measure preload until you find a good range, what I've read about LS7 lifters, between .060 and .100 is acceptable with around .080" being somewhat ideal.

So for example, start with 7.4 on the checker, install the rocker arm, tighten the bolt to zero lash then set the dial indicator and zero it. Torque down the rocker bolt, wait a moment or two for the oil to leave the lifter and measure what the preload is. If it's too high, then start over with the checker at 7.35.

budhayes3

iTrader: (19)

This is my favorite sticky :

https://www.performancetrucks.net/fo...d.php?t=440262

Richard at WCCH recommends .040 to .080, .060 being ideal

Preston129

iTrader: (3)

Good info, I stand corrected

Ferocity02

iTrader: (59)

Fortunately these LS lifters are pretty lenient with preload. I've seen people running .030 to .120, although I wouldn't recommend either of these. I'm going to shoot for 0.080. I went ahead and ordered a Comp pushrod length checker for my rebuild. For $16 is cheap insurance. I also ordered a set of 7.350" pushrods. If I don't need them, I will sell them.