Another pushrod length thread...
Thread Starter
Joined: Nov 2004
Posts: 309
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From: Metro Detroit
Another pushrod length thread... Ok, set up is as follows. Milled 799 ls6 castings to 62cc's, .04 gasket using stock rockers with the turrion upgrade.
I have the push rod length checker but I can't seem to get an accurate reading with the new LS7 lifters... My question is what's the best way to go about this with lifters that aren't pumped up with oil? I'm assuming stock 7.400 length pushrods will be too long and I'll need to go with something shorter.
I have the push rod length checker but I can't seem to get an accurate reading with the new LS7 lifters... My question is what's the best way to go about this with lifters that aren't pumped up with oil? I'm assuming stock 7.400 length pushrods will be too long and I'll need to go with something shorter.
Just run the push rod out until you hit zero lash. Tighten rockers down just pretty snug. I soaked my lifters for a bit, don't Know that it helped but don't guess it could have hurt. Make sure that cam is on base circle though, thats the most important thing.
Thread Starter
Joined: Nov 2004
Posts: 309
Likes: 0
From: Metro Detroit
So you would use the length that the checker is at, right before the lifter starts to compress?
I believe that's your problem - you have zero oil pressure in your lifter with ~400# springs pushing down on the cup through a flimsy measurement tool. Your lifter cup is compressing and your checker tool is deflecting. I'll bet the combined effect is causing your inconsistency problems.
Buy yourself a set of these: http://www.goodson.com/VTS-8_-Heavy-...cking_Springs/.
Also enables you to manipulate the valve by hand when checking ptv instead of having to turn over the engine.
Buy yourself a set of these: http://www.goodson.com/VTS-8_-Heavy-...cking_Springs/.
Also enables you to manipulate the valve by hand when checking ptv instead of having to turn over the engine.
Last edited by ckpitt55; Jun 3, 2013 at 01:36 PM.
I can't remember exactly how it went, but there is some method people use involving zero lash and how many turns it takes to get to torque specs. I checked mine using the process and it seemed to work. It was something like once you get the rocker snugged just enough to where it quit moving, adjust the PR checker to zero lash and I believe it was something like 1 1/4- 1 3/4 turns until you reach torque specs is what your after. CHECK THE AMOUNT OF TURNS! I'm not sure that's the correct amount, but if your search PR length enough, you'll find what I'm talking about.
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Put the cam on the base circle. TDC on the compression stroke is fine.
Set your checking pushrod to 7.3". Install it, snug the rocker down. The rocker will be loose....you can move it up and down. If it's not loose, shorten and try again.
Keep lengthing the pushrod until the rocker won't move. It's a bit touchy, but you will know when you get it.
Measure the pushrod.
Add how much you want the preload to be.
Order your new pushrods.
You probably won't find the exact length, unless you buy custom. But you can get close enough.
Ron
Set your checking pushrod to 7.3". Install it, snug the rocker down. The rocker will be loose....you can move it up and down. If it's not loose, shorten and try again.
Keep lengthing the pushrod until the rocker won't move. It's a bit touchy, but you will know when you get it.
Measure the pushrod.
Add how much you want the preload to be.
Order your new pushrods.
You probably won't find the exact length, unless you buy custom. But you can get close enough.
Ron
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Going to run mine at .105 two full turns to 22 ft pounds. The ls7 lifters can have anywhere from .166 to .200 travel. Next shortest pushrod gave me to little preload. This is with a 7.375.
On an all aluminium motor you will loose preload when it warms up.
Some run as much as .120
On an all aluminium motor you will loose preload when it warms up.
Some run as much as .120