lifter preload

[strokin96xj]

hi i was just wondering how important it is to check lifter preload. i do not have the tools to check this but on my motor build i bought a new crane cam, new crane cam lifters, new 4.0 liter pushrods, and new rocker arms and bridges. thanks for the help just need some answers before i start it for the first time and break it in.

[YJ_and_Corey]

Ok, this may be the MOST important measurement you make.

Can't believe someone else didn't jump on this, but here is what I do:

1) Once the engine is assembled, turn the engine over slowly by hand 3-4 times. This will allow the lifters to "bleed down" and makes sure they are all collapsed.

2) Bring the engine up to TDC on one, just watch the number one springs to do this (or the timing marks on the harmonic)

3) Rotate the rockers on 1 back, away from the valve. You can always do this by hand (if you can't you obviously need much shorter pushrods).

4) Once rocked back away from the valve, slip a feeler gauge between the top of the valve and the bottom of the rocker arm.

5) 80 - 100 thousands is acceptable. Anything outside that range is not. Simple.

[strokin96xj]

alright thanks alot

[Biggrnjeep97]

These five steps should be stickied somewhere so nobodys doin this later >
-Will

[SilverXJ]

That isn't actually checking preload. What is being checked in that method is how much the lifter will travel until it bottoms out.

I prefer a method of the sort here: http://cranecams.com/?show=techarticle&id=2

Fast and Easy Way to Check Hydraulic Lifter Preload when using Non-Adjustable Rocker Arms

With the cam, hydraulic lifters and pushrods in place, install your rocker arm assembly. Use the prescribed method in your repair manual and torque down all the valve train bolts in the proper sequence. Pick a cylinder that you are going to check. Hand rotate the engine in its normal direction of rotation until both valves are closed. You are on the compression cycle for that cylinder. (At this position the valve springs are at their least amount of tension making the job a little easier to do.)

Wait a few minutes, allowing the lifters to bleed down. Now, lay a rigid straightedge across the cylinder head, supporting it on the surface of the head where the valve cover gasket would go. Using a metal scribe and the straightedge, carefully scribe a line on both pushrods. Now carefully remove the torque from all valve train bolts, removing any pressure from the pushrods. Wait a few minutes for the pushrod seat in the hydraulic lifter to move back to the neutral position. Carefully scribe a new line on both pushrods.

Measure the distance between the two scribe marks, it represents the amount of lifter preload. If the lines are .020" to .060" apart you have proper lifter preload. If the lines are the same or less than .020" apart you have no, or insufficient, preload. If the lines are further apart than .060", you have excessive lifter preload.

[YJ_and_Corey]

That isn't actually checking preload. What is being checked in that method is how much the lifter will travel until it bottoms out.

I prefer a method of the sort here: http://cranecams.com/?show=techarticle&id=2

Fast and Easy Way to Check Hydraulic Lifter Preload when using Non-Adjustable Rocker Arms

With the cam, hydraulic lifters and pushrods in place, install your rocker arm assembly. Use the prescribed method in your repair manual and torque down all the valve train bolts in the proper sequence. Pick a cylinder that you are going to check. Hand rotate the engine in its normal direction of rotation until both valves are closed. You are on the compression cycle for that cylinder. (At this position the valve springs are at their least amount of tension making the job a little easier to do.)

Wait a few minutes, allowing the lifters to bleed down. Now, lay a rigid straightedge across the cylinder head, supporting it on the surface of the head where the valve cover gasket would go. Using a metal scribe and the straightedge, carefully scribe a line on both pushrods. Now carefully remove the torque from all valve train bolts, removing any pressure from the pushrods. Wait a few minutes for the pushrod seat in the hydraulic lifter to move back to the neutral position. Carefully scribe a new line on both pushrods.

Measure the distance between the two scribe marks, it represents the amount of lifter preload. If the lines are .020" to .060" apart you have proper lifter preload. If the lines are the same or less than .020" apart you have no, or insufficient, preload. If the lines are further apart than .060", you have excessive lifter preload.

Respectfully as possible - what the above amounts to ^^^^ is exactly what I described doing. Checking lifter pre-load.

Trust me here. I've build many stroker inline sixes. Please phone a competent engine rebuilding shop if you doubt my method.

[SilverXJ]

What you are describing, as I said, is how much further the lifter will travel before it bottoms out. As different lifters are designed differently it tells you nothing about preload, nor does it tell anything about how far you are from zero lash.

For example. I have a lifter here that will compress fully .222". Using your method on this lifter would put the preload at .159" to .172" (With rocker arm ratio taken into account; .100"/1.6=.0625", .080"/1.6=.05"). Most flat tappet hydraulic lifter specs with in .020"-.060" or preload. Also, with a higher preload of .060" the lifter in question would have .162" prior to bottoming out, which would be .2592" at the valve. Again, you are seeing how much further the lifter has left to compress, not how much it has already compressed.

I also have rebuilt several inline sizes as well as several different engines.

Edit: to further illustrate my point, I checked a completely different lifter which compresses .119". Again, using your method it would net a preload of .0565"-.069". This also shows that lifters are built differently and their full compression differs.

[Exos]

What you are describing, as I said, is how much further the lifter will travel before it bottoms out. As different lifters are designed differently it tells you nothing about preload, nor does it tell anything about how far you are from zero lash.

For example. I have a lifter here that will compress fully .222". Using your method on this lifter would put the preload at .159" to .172" (With rocker arm ratio taken into account; .100"/1.6=.0625", .080"/1.6=.05"). Most flat tappet hydraulic lifter specs with in .020"-.060" or preload. Also, with a higher preload of .060" the lifter in question would have .162" prior to bottoming out, which would be .2592" at the valve. Again, you are seeing how much further the lifter has left to compress, not how much it has already compressed.

I also have rebuilt several inline sizes as well as several different engines.

Edit: to further illustrate my point, I checked a completely different lifter which compresses .119". Again, using your method it would net a preload of .0565"-.069". This also shows that lifters are built differently and their full compression differs.

I agree completely. What you are measuring YJ is part of the lifter valve spring travel before bottoming out. Nothing to do with preload on an hydraulic lifter.

[YJ_and_Corey]

What you are describing, as I said, is how much further the lifter will travel before it bottoms out. As different lifters are designed differently it tells you nothing about preload, nor does it tell anything about how far you are from zero lash.

For example. I have a lifter here that will compress fully .222". Using your method on this lifter would put the preload at .159" to .172" (With rocker arm ratio taken into account; .100"/1.6=.0625", .080"/1.6=.05"). Most flat tappet hydraulic lifter specs with in .020"-.060" or preload. Also, with a higher preload of .060" the lifter in question would have .162" prior to bottoming out, which would be .2592" at the valve. Again, you are seeing how much further the lifter has left to compress, not how much it has already compressed.

I also have rebuilt several inline sizes as well as several different engines.

Edit: to further illustrate my point, I checked a completely different lifter which compresses .119". Again, using your method it would net a preload of .0565"-.069". This also shows that lifters are built differently and their full compression differs.

I agree completely. What you are measuring YJ is part of the lifter valve spring travel before bottoming out. Nothing to do with preload on an hydraulic lifter.

Right. And the OP that asked wanted an answer that would work quickly for him.
My method ensures his engine will not self-destruct on start-up. He obviously doesn't know or care about finding the precise lifter preload on his engine. It's a quick google search for anyone with
computer.

Your methods are technically correct, but unnecessary unless the block and head have been decked excessively or the rocker ratio has been altered.

[Exos]

Block decked, head shaved, whatever... preload is preload. My stroker has been decked and shaved. A good understanding of preload is mandatory. And still, your method does not measure preaload. It only measures what"s left of lifter travel after whatever torque you put. Sorry to say, but it's worthless on proper preload.

I have adjustable lifters though... that maybe different with non ajustable. But still you'd have to measure preload, not lifter compression.

let me rephrase this : you have to measure between zero lash and the torque value of the lifter.

You see: your method will onlly measure what's left of play in the lifter after WHATEVER torque you put.... doesn't measure anything.

[YJ_and_Corey]

Block decked, head shaved, whatever... preload is preload. My stroker has been decked and shaved. A good understanding of preload is mandatory. And still, your method does not measure preaload. It only measures what"s left of lifter travel after whatever torque you put. Sorry to say, but it's worthless on proper preload.

I have adjustable lifters though... that maybe different with non ajustable. But still you'd have to measure preload, not lifter compression.

let me rephrase this : you have to measure between zero lash and the torque value of the lifter.

You see: your method will onlly measure what's left of play in the lifter after WHATEVER torque you put.... doesn't measure anything.

This ^^^ is basically armchair logic.

Of course my method measures something. It measures how much room exists internally in the lifter before it bottoms out. Which is far more important than what you turkeys are measuring, which is basically the internal travel in the lifter from static to placing oil pressure back up the valvetrain and onto the top of the valve.

A good anti-pump up, self-adjusting lifter like the Comp ones I use, has large amounts of internal travel. Do you fellows actually understand how a hydraulic lifter works? What you guys seem to have missed is that good aftermarket lifters like the ones we use (or I hope "we" use) can compensate for huge amounts of variance in valvetrain geometry.

*And WTF is torque value of a lifter? Do you mean "on" a lifter? You have adjustable rockers so you should set your preload very low, as close to zero as you are comfortable with, and check it periodically*

When I am bolting rockers down, I have that cylinder at TDC. I feel each pushrod and spin it slowly as I tighten down the bolt. We want the rod to "just" stop turning as it tightens down. I already know, before I use my method, that I am within acceptable preload limits. But rotating the rocker back and slipping a feeler gauge underneath is insurance.

[SilverXJ]

Of course my method measures something. It measures how much room exists internally in the lifter before it bottoms out. Which is far more important than what you turkeys are measuring, which is basically the internal travel in the lifter from static to placing oil pressure back up the valvetrain and onto the top of the valve.

What you are measuring is a safety margin. Setting the preload correctly (which your method does not) negates this measurement.

[Exos]

Of course my method measures something. It measures how much room exists internally in the lifter before it bottoms out.

That's right. You said it yourself.

And I left the "turkeys" part out, as I'm sure every turkey here saw it.

[dwg86]

I am no lifter engineer, but I have always read .040-.060 lifter preload. With stud mounted roller rockers I have read, and always used 1/2 turn, with no problems.

[SilverXJ]

While I don't like the generic rule on adjustable of 1/2 turn due to the fact that different threads could come in to question, on Harland Sharp's adjustable rockers, 1/2 turn = .024" of preload.