Carlisle

iTrader: (1)

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.

Darkman

iTrader: (2)

https://ls1tech.com/forums/11999768-post2.html

RonSSNova

iTrader: (3)

https://ls1tech.com/forums/generatio...surements.html

My thread from a couple of weeks ago.

Ron

Carlisle

iTrader: (1)

Hey thanks guys, when I searched I somehow missed those. I'm slowly piecing all of this together. Question, how do I know what preload I need? And when I'm trying to get zero lash, what 'tick tick' noise am I looking for? From the lifter?
Thanks,
C.

RonSSNova

iTrader: (3)

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.

mark21742

FYI I am running ls7 lifters and run about 1/2-3/4 turn to torque from 0 lash

Carlisle

iTrader: (1)

Understood, I think I got the hang of it now. Real quick, sort of off topic, once you get the correct length pushrod and install them, do you torque the roller rockers at TDC?
C.

I read about this method just a little bit ago, it makes sense, but I understand the adj. pushrod method better, so I'll probably do that.

C.

ZeeOSix

That's only about 0.013~0.032" of pre-load. Why so low of a pre-load on LS7 lifters?

vettenuts

iTrader: (4)

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

mark21742

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

mark21742

It works good if you already have a pushrod to base your measurements off of

dr_whigham

iTrader: (49)

Can I jump in here real quick and ask a Q?

Manton 11/32 push rods.... these fit a stock 243, correct? it's the 3/8 that do NOT, right?

Thanks OP

mark21742

Never tried, but pretty sure 3/8 push rods would be too wide....couldn't tell you about the 11/32 though....might want to call a sponsor on that one

vettenuts

iTrader: (4)

I am pretty sure that they do but best to verify. There were some threads that I seem to remember they fit. Have you searched here? If not here maybe I saw them on Corvetteforum.

I went double taper because straight 3/8 wouldn't fit the AFR heads.

Carlisle

iTrader: (1)

What size pushrods did you use with the 205s? I'm doing pretty much the same swap in May, milled 205s and YT's.

C.

soundengineer

iTrader: (16)

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.

ZeeOSix

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.

ZeeOSix

It's not that simple. You haven't read up on the 50 threads about pushrod lenght and lifter pre-load.


Condensed version:
https://ls1tech.com/forums/16104691-post85.html

vettenuts

iTrader: (4)

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.

dr_whigham

iTrader: (49)

Thanks guys. And yes, vettenuts, I've read your threads. AWESOME posts, BTW.

Apologies to the OP. Thanks again.