mattz06

using a factory style crane lifter, when checking lifter preload and proper pushrod length, after tightening the stock rockers to 22ftlbs, how much should the pushrod spin?

any write ups on this?

Country Boy

iTrader: (24)

NONE! a spinning pushrod is lash, not preload.

mattz06

shouldn't it spin until you torque the rocker, then stop?

1999_SS_M6

you have to be careful telling him that he should get no spin.. He's obviously a little unsure about setting up a valvetrain, and since he doesn't know lash from preload, if you tell him "no spin" he might just go out there and start wrenching. Who's to say that he knows you have to rotate the engine and set valve lash in sequence?

Carl's right though Matt.. You're asking about valve lash adjustment, not lifter preload. You'll need some info to do this properly, because you want to only adjust the valve lash for the valves that are closed. I would recommend you get a book that will tell you the procedure for that rather than just trying to look at the springs, rotating the engine and finishing the procedure, especially since it's your first time out. The way most people go is to spin the pushrod between your fingers as you tighten the rocker bolt. It will spin very freely, with no resistance, and just as you feel the rocker tighen to the top of the pushrod, you will feel the slightest amount of drag... MIND YOU, the pushrod will still spin, but now it will have just the slightest amount of friction since it is fully seated between the lifter and the rocker arm. That is zero lash. From this point it's opinion time... you'll hear everyone say anything from 1/2 additional turn to 1 full turn. I generally go around 3/4. It's trial and error though, that's why people opted for an "adjustable" valvetrain in the first place.

I hope you were talking about an aftermarket adjustable rocker, because none of this applies to your stockers.. you just torque them to 22ft/lbs and go. I would hate to think we just went through all that because you were twisting on your stockers and just got curious. lol

mattz06

stock rockers, sounds like I just can use a pushrod length checker, bring it up to touch the rocker when the valve is closed and the rocker is tightened to 22ftlbs.
then add the lifter preload to the pushrod length. right?

FASTONE

The stock rockers are NOT adjustable you set them at 22 lbs torque.If you have an adjustable rockerarm system then you worry about preload on the lifter.Also you may need to check the lenth of your pushrod,this is NOT for beginners.

mattz06

I KNOW THE stock rockers are not adjustable. BUT YOU DO have to worry about preload on the lifter when you're installing new pushrods with milled heads

DaleMX

iTrader: (4)

Sure, go check this out.

http://www.compcams.com/information/Products/Pushrods/

Dale

DaleMX

iTrader: (4)

Keep in mind that he is using AFR heads. We dont know about the mount for the rockers and the valve length on those heads. He should check out the pushrod length for sure. Quite honestly if it were me I would invest in a set of adjustables and high valve covers and adjust them that way.

mattz06

"Determine correct valve train geometry
What is the correct length pushrod for your application? The one that produces correct valve train geometry. What is correct valve train geometry? When the rocker arm roller tip rolls from the intake side of the valve tip, across the center of the tip (at approximately mid-lift), to the exhaust side of the valve tip (at full lift) and back."


I understand what comp is saying about the rocker properly rolling over the valve tip.

but my question is, then will the lifter preload automatically be correct?

soundengineer

iTrader: (16)

Are you using stock Rockers?? non adjustable??
Are you using stock style lifters??? - yes from above posts
Are you using stock heads??? and do you have the right length pushrods for the heads???

If you answered yes-yes-yes-yes
then the proper procedure is to find TDC at each piston and torque rockers to 22ft/lbs
I recommend TDC on the combustion stroke because some cams overlap at TDC and the valves will not be closed if you use the exhaust/intakle stroke.
you can do one set on the drivers side..and one set on the passenger side at the same time- that's 1 & 6, rotate 90, 8 & 5, rotate 90, 7 & 4, rotate 90, 3 & 2.

LS1 Engine
Piston #'s
.............
....8-7....
....6-5....
....4-3....
....2-1....
...front...

BOWTIE

With out trying to read more into your question, with a new lifter the pushrod will continue to spin until after you have completely bottomed out the plunger which is way too much preload. All the lifter has is a small spring pushing the plunger up to the top of the lifter, you can completely collapse that spring and still be able to turn the push rod. If you read a procedure for adjusting hydraulics on an adjustable style valve train it will describe zero lash as when you start to feel the slightest resistance in spinning the pushrod. They will aslo tell you to adjust the intake when the exhaust starts to open and adjust the exhaust as the intake is almost all the way closed (turning the motor in the direction of rotattion of course), this becomes more critical the bigger the cam gets.