Lifter preload & pushrod length?
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From: Ft. Campbell, KY/TN
Lifter preload & pushrod length? I'm trying to find detail instructions on how to find the correct pushrod length I'm going to need for my H/C build. Got a set of milled 205cc AFR's going on, and most likely a set of Yella Terras. A few things are confusing, lifter preload is one of them. Anyone care to enlighten me?
Also, I was going to go with a set of LS7 lifters, anyone care to comment? good or bad.
Thanks,
C.
Also, I was going to go with a set of LS7 lifters, anyone care to comment? good or bad.
Thanks,
C.
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From: Ft. Campbell, KY/TN
Thanks,
C.
I didn't read Vettenuts deal real close. But I think it means when you are moving the rocker up and down by hand. Too short of a pushrod allows movement and the rocker will make a ticking sound. This is when you are sneaking up on the 0 lash length.
It is basically a pain in the A$$ because you can't adj the pushrod when the rockers are on. That was why as soon as I got it close, I just used a feeler gauge to measure the clearance between the rocker and the valve tip and divided by 1.7 then add this length to the pushrod to get the 0 lash length.
It is basically a pain in the A$$ because you can't adj the pushrod when the rockers are on. That was why as soon as I got it close, I just used a feeler gauge to measure the clearance between the rocker and the valve tip and divided by 1.7 then add this length to the pushrod to get the 0 lash length.
Thread Starter
On The Tree
iTrader: (1)
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From: Ft. Campbell, KY/TN
I didn't read Vettenuts deal real close. But I think it means when you are moving the rocker up and down by hand. Too short of a pushrod allows movement and the rocker will make a ticking sound. This is when you are sneaking up on the 0 lash length.
It is basically a pain in the A$$ because you can't adj the pushrod when the rockers are on. That was why as soon as I got it close, I just used a feeler gauge to measure the clearance between the rocker and the valve tip and divided by 1.7 then add this length to the pushrod to get the 0 lash length.
It is basically a pain in the A$$ because you can't adj the pushrod when the rockers are on. That was why as soon as I got it close, I just used a feeler gauge to measure the clearance between the rocker and the valve tip and divided by 1.7 then add this length to the pushrod to get the 0 lash length.
C.
C.
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With the Yella Terra's, you must first set the wipe pattern on the rockers. Don't measure or buy pushrods until you do. Here is a link that will hopefully help set up the rockers. Don't follow LS1howto for the rockers, it is wrong.
Link
Pushrod stiffness is also key to valve train control at high RPM. Here is a link to some information on pushrod stiffness.
Link
Hope these links provide some help and guidance
Link
Pushrod stiffness is also key to valve train control at high RPM. Here is a link to some information on pushrod stiffness.
Link
Hope these links provide some help and guidance
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From: PA/MD
I spin mine up to 8,000rpms, and even with the light preload they are good and quiet at idle and low rpms. Plus I'm running a melling high volume/pressure pump...3/4 turn is what i have always shot for and never had any problems
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From: PA/MD
I went double taper because straight 3/8 wouldn't fit the AFR heads.
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From: Ft. Campbell, KY/TN
C.
once you measure for Pushrod length....
you can figure out your preload by simple math...
the threads on the rocker are a 1.25 pitch...
so 1.25/25.4 = 0.049213 per 1 full rotation from Zero Lash
with a stock cam you want about .080~.100 preload..
with an aftermarket cam(which is made from a different material than stock) you want .020~.040 which is 3/8 turn to Just under 7/8 turn from zero lash to 22ftlbs
the Ideal point being 5/8 or right at .030 on most aftermarket cams..(contact your cam vendor for their recommendation)
you can adjust your total preload by changing your pushrod length
what you will find is that when you have the proper preload...your valvetrain will get considerably more quiet...of course, its all relative to how extreme your cam is.
I have a pretty extreme cam with large duration and big lift, so its gonna make some noise from the valves slamming shut...but the actual valvetrain lifter noise is very minimal.
you can figure out your preload by simple math...
the threads on the rocker are a 1.25 pitch...
so 1.25/25.4 = 0.049213 per 1 full rotation from Zero Lash
with a stock cam you want about .080~.100 preload..
with an aftermarket cam(which is made from a different material than stock) you want .020~.040 which is 3/8 turn to Just under 7/8 turn from zero lash to 22ftlbs
the Ideal point being 5/8 or right at .030 on most aftermarket cams..(contact your cam vendor for their recommendation)
you can adjust your total preload by changing your pushrod length
what you will find is that when you have the proper preload...your valvetrain will get considerably more quiet...of course, its all relative to how extreme your cam is.
I have a pretty extreme cam with large duration and big lift, so its gonna make some noise from the valves slamming shut...but the actual valvetrain lifter noise is very minimal.
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I've got the 11/32" Mantons with 0.120" wall pushrods in my LS6. They fit fine through the holes with no rubbing. I've got some posts buried here someplace showing them. A search can probably find the posts.
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Condensed version:
https://ls1tech.com/forums/16104691-post85.html
My heads required a 0.125 shim to correct for rocker geometry so the pushrod length I am using is likely different than what you may need. As for diameter and reasons for using what I did, the post above includes a link to why I went with the double taper pushrods.
