03RCSB

iTrader: (2)

Didn't want to make a new thread about something that has been discussed countless times but paranoia is getting the best of me.

I just pulled my 2003 5.3l apart to do the ls7 lifters and I'm using the comp pushrod measuring tool. TR220 cam and graphite ls1 head gaskets which are .054", heads are stock and not milled.

I checked four different valves, making sure I was off the cam lobe and this is what I got,

About 8.75 - 9 turns on the pushrod tool so I did (8.85 x .050") = .4425" and added that to the 6.8" length of the tool which gave me a 7.2425 length. So with the 7.3" pushrods I've got about a .0575" preload which I searched and found to be acceptable and should quiet the valvetrain down some.

Now my question is that in all of my searches, I've never seen anyone with pushrods this short. Am I being paranoid and it's possible that they just need to be that short or is it that I might have goofed somewhere?

Thanks guys

jrmchevyman

Texas Speed 5/16" Chrome-moly Pushrods, SINGLE

They have the size you need, look under the options drop down menu.

I'd probably use stock size or next size down from stock.

Let others chime in though, I did not have to pull my heads so I'm on stock gaskets and I used the stock sized 7.400 pushrods.

03RCSB

iTrader: (2)

Thats what I was originally using as well. I ran the Comp 7.4" pushrods for 300 or so miles before a lifter started acting up. With the taller cup of the ls7 lifter and removing the head and such I had read I should remeasure.

I would guess being on the shorter side wouldn't hurt anything, truck just wouldnt run right and it would be a $100 mistake as opposed to the rods being too long and me breaking something which who knows what it would cost.

I just got worried when I see my measured length comes out a decent amount shorter than what ive seen everyone else on here measure to.

budhayes3

iTrader: (19)

That does sound shorter than anything that I've heard of with stock heads, even with the LS7 lifters. There was recently a post around here that stated that the LS7 lifter cups actually aren't taller and that it's just an optical illusion, so now it appears that there is some debate on that As you mentioned, I'd rather be shorter than longer on the pushrods, especially since you lost a lifter already with the 7.4's. Are you positive that you're getting 0 lash with the pushrod checker? I know that it can be tough to get your fingers in there to turn it.

Gonna move this to the internal engine mod section to see if we can get more hits from the seasoned engines guys around here also

Atomic

iTrader: (42)

I loosen up the rocker and turn the checker half a turn at a time when I know im close.

03RCSB

iTrader: (2)

Thanks for the move Bud, if its not pouring rain when I get home tonight I'm going to head back outside to check again. At least I know it was warranted to question the length.

smokeshow

iTrader: (16)

I measured an LS7 vs a stock lifter some time ago, and there was a 50 or 60 thousandths difference.

Optical illusions can be tricky sometimes...

03RCSB

iTrader: (2)

I just checked again on two different valves than the initial four I tried and I'm getting the same measurements. As long as noone sees any issues with the math above I guess I'm going to try the 7.3".

I put some pressure on the pushrod as I spun the crank to make sure I was off of the cam lobe and then bolted down the rocker, no wiggle room and if I backed the tool down a hair there was a slight tap back and forth with the rocker so.

What should I be looking for in the behavior of the engine to tell me if these are too short?

Atomic

iTrader: (42)

Lots of valve train noise

03RCSB

iTrader: (2)

Would it be safer to go with the 7.325" PR and have .0825" preload or stay with the 7.3" PR and run .0575" preload?