Lifter preload (Page 1/2)
Lilchief MAY 28, 12:02 AM
What are the pros and cons of setting your lifters at 3/4s turn over 1 1/2 turns ? The 3/4 is .060 preload and 1 1/2 is .120 almost a 1/8 inch . This is on my 3.4.
Modesto MAY 28, 12:11 AM
I just set mine today. The Comp lifters I used only called for half a turn (.030) while the facotry service manual calls for the 1.5 turns. I used Comp's recommendation I'm using their lifters and not GM's.



I would think that depending on what the lifter was designed to operate with, it would increase load and therefore accelerate wear on the lifter and cam. In an extreme case I suppose it may cause cam failure during break in, but I'm sure that would take more than the difference of a single turn.

Patrick MAY 28, 12:48 AM

I spent a lot of time researching how to set the lifter pre-load on my Formula's 2.8 when I installed the 1.6 roller-tip rockers. I think plenty of people, especially novices, totally screw up when it comes to determining zero lash.

Anyway, it's Here if you wish to read it.
theogre MAY 28, 12:57 AM
In general w/ any hydro lifters...
You only need bare minimum preload to compress the lifters so can't hammer and make noise or worse break small clip on top of lifters plus adds tolerance for Push Rods, valves, etc for engine hot vs cold.

Find FSM etc w/ correct preload data. Aftermarket setup try calling the makers of that.
If that doesn't help, watch the lifters while adjusting the rockers. Very Small adjustment of the rocker can be a lot bigger at PR tips because of level action of rockers.
IOW Small changes at rockers can slam the lifters at top or bottom of travel and quickly wreck the valve train.

Part of L4 valve noise is because can't set preload as engine wears valve parts. More so w/ Duke engines w/ 100,000 miles or more on them.

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Raydar MAY 28, 07:32 PM
Whatever spec you choose...
I have usually heard that you are supposed to spin the pushrods, and tighten the rocker nut until they become more difficult to spin.
The trouble is that today's lubricants are so good, that it becomes impossible (at least for me) to tell when the slack is gone.
Instead of doing that, rattle the pushrod back and forth. When the slack is gone, it will become readily apparent. (And it will still be easy to spin.)

Just one man's opinion.
fieroguru MAY 28, 07:35 PM
The trend with lifter design is less and less preload, so make sure to follow the specs for the lifters you install.
Patrick MAY 28, 08:40 PM

quote
Originally posted by Raydar:

I have usually heard that you are supposed to spin the pushrods, and tighten the rocker nut until they become more difficult to spin.
The trouble is that today's lubricants are so good, that it becomes impossible (at least for me) to tell when the slack is gone.




I agree, that method makes no sense whatsoever.
Lilchief MAY 28, 09:02 PM
Well I have the intake off. And I'm using a dial indicator with an extension. The extension goes on the piston/plunger in the lifter. Set indicator to zero and tighten to desired preload. I chose .060, 3/4 turn. My engine builder suggest .050. I might contact the seller (ARI?) and see what they say.
Patrick MAY 29, 01:45 AM

quote
Originally posted by Lilchief:

Well I have the intake off. And I'm using a dial indicator with an extension. The extension goes on the piston/plunger in the lifter...



Can you take a picture of what you're doing? Perhaps I'm the only one, but I've got no idea what you're describing.

Dennis LaGrua MAY 29, 08:49 AM
If done correctly adjusting hydraulic lifters can be an easy procedure. He is a fool proof method.
Remove the spark plugs. Make sure all rockers are loose. Set the balancer to the timing mark. Now go to every pushrod,push up and down until no motion is felt. Tighten rocker just to the no slack point but not tighter. Then rotate engine 1/4 turn, check each push rod for no up down movement. Rotate another 1/4 turn and do the same. Continue doing this for two entire revolutions of the balancer. When you are done just go to each rocker arm and give it the recommended preload turn.

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[This message has been edited by Dennis LaGrua (edited 06-05-2020).]