How do I preload lifters?
How do I preload lifters? I am putting back together a friends 350 and I have a package of new hydraulic roller lifters where the instructions say "Do not pre-pump lifters with oil"
Also, when I take the new lifters out of the package and place it on my workbench and stick a pushrod in the top of the lifter I try to push down on the plunger and I cant budge it.
In the past I would take lifters, soak them in a little ATF and push the plunger up and down until the plunger would no longer press in thus "pumping up" the lifter. Then I would install all 16 lifters and when I torqued the rocker not down to "0" lash I would give 1/2 a turn to set the preload. At first the rocker would stay firm pressed on the spring but after a minute or so the lifter would bleed down and the rocker would become loose again confirming that I did no bottom out the lifter plunger and the preload was correct. Then I would move onto the next valve.
My 3 questions are:
1. Why cant I move the plunger on these new lifters?
2. How would I set preload on empty lifters?
3. Why would you NOT pump up lifter prior to install? The all bleed back down to where they want to be well before you start the engine anyway.
Also, when I take the new lifters out of the package and place it on my workbench and stick a pushrod in the top of the lifter I try to push down on the plunger and I cant budge it.
In the past I would take lifters, soak them in a little ATF and push the plunger up and down until the plunger would no longer press in thus "pumping up" the lifter. Then I would install all 16 lifters and when I torqued the rocker not down to "0" lash I would give 1/2 a turn to set the preload. At first the rocker would stay firm pressed on the spring but after a minute or so the lifter would bleed down and the rocker would become loose again confirming that I did no bottom out the lifter plunger and the preload was correct. Then I would move onto the next valve.
My 3 questions are:
1. Why cant I move the plunger on these new lifters?
2. How would I set preload on empty lifters?
3. Why would you NOT pump up lifter prior to install? The all bleed back down to where they want to be well before you start the engine anyway.
I guess I will just drop them in and set preload like I normally would even though they are empty. The resistance I am getting trying to push the plunger in by hand should be enough to determine "0" lash when I torque the rocker nut.
The old lifters I can take a pushrod and press hard on the plunger and the plunger will bottom out. The new lifters came straight out of the package and should not be full of oil and I push with all my might and none budge. Package said hydraulic I hope these aren't solids.
Trending Topics
TECH Veteran
Joined: Dec 2008
Posts: 4,145
Likes: 61
From: Little Rock, AR
The old lifters I can take a pushrod and press hard on the plunger and the plunger will bottom out. The new lifters came straight out of the package and should not be full of oil and I push with all my might and none budge. Package said hydraulic I hope these aren't solids.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Banned
Joined: Jan 2013
Posts: 588
Likes: 0
From: Las Vegas
It means u have a strong spring under the cup. Myself i think that is a good thing. When u set the preload the vlv should stay shut until the plunger is fully bottomed out. U should see a vlv open if u over adj the preload. Or u could connect a air hose/supply to the sparkplug hole and listen for air flow into the manifold.
Set preload same for dry or prelubed lifter. Important terms are "base circle" and "zero lash". If u dont have those nailed your not gonna do it right. Zero lash is same whether oil inside lifter or not - the cup hasnt moved down yet at all. If u need to google up a hyd lifter diagram and see for yourself.
Another important item is what lifter your using. Original style hyd lifters use 1/4 to 1 full turn preload. New LS7 lifters take only 1/4 turn preload or less. Again if lifter bottoms out it will move the vlv open - u should look for this.
Set preload same for dry or prelubed lifter. Important terms are "base circle" and "zero lash". If u dont have those nailed your not gonna do it right. Zero lash is same whether oil inside lifter or not - the cup hasnt moved down yet at all. If u need to google up a hyd lifter diagram and see for yourself.
Another important item is what lifter your using. Original style hyd lifters use 1/4 to 1 full turn preload. New LS7 lifters take only 1/4 turn preload or less. Again if lifter bottoms out it will move the vlv open - u should look for this.
TECH Veteran
Joined: Dec 2008
Posts: 4,145
Likes: 61
From: Little Rock, AR
The preload range is the same on the LS7s. They are the replacement lifters for the LT1. They have plenty of travel, just like the original ones.