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Old 09-13-2020, 11:32 AM
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Default Confirming valve adjustment

I'm chasing a potential ticking Comp 857 lifter on Old Faithful. Not sure it is a lifter at this point, but I want to confirm my understanding of some things before I go further.

It feels to me like there are about two full turns from zero lash until the plunger bottoms out in the lifter. At 20 threads per inch on a 7/16 rocker stud, that's about .100 inches of plunger travel, right?

Ok, so now I set the valves last night using EOIC. Car hasn't run in a few days. I set them at 1/2 turn past zero lash per Comp's instructions, but when I tightened the set screw they all went another 1/4 turn or so. So again, at 20 threads per inch, .05 inches per full turn of the poly lock, at 3/4 turn, I'm probably looking at .035 inches of preload or so.

So what I was thinking of doing to double-check is to go through the firing order again. This time, I was going to push the back of the rocker all the way down to bottom the plunger, put a dial indicator on the rocker, and see how far up the plunger comes. I'm expecting to see about .065 inches of travel.

Does this make sense? At that point, I plan to test drive the car. If I still have the noise, I plan to add another half turn to each and see if the noise changes.


I guess I'm assuming after a few days of sitting and a few rotations through the firing order with a bump starter that I'll be able to push the rockers all the way down by hand.

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Old 09-13-2020, 12:14 PM
78w72 78w72 is offline
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i dont have the answer but the math makes sense... but will follow the thread to see how that process works out for you.

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Old 09-13-2020, 12:36 PM
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Originally Posted by 78w72 View Post
i dont have the answer but the math makes sense... but will follow the thread to see how that process works out for you.
Will do the same ^

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Old 09-13-2020, 05:44 PM
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the more i think about it, a feeler gauge is probably easier. why try mounting up the dial indicator, especially with an aluminum head, when i can just press down on the pushrod side of the rocker and put a feeler gauge between the rocker tip and valve stem?

i guess if i do it that way i need to consider the rocker ratio in the math. i am thinking if a .030 feeler gauge is the biggest that fits between the valve stem and rocker tip, that means the plunger is .020 from being bottomed out?

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Old 09-14-2020, 02:18 AM
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Your math sounds fine. Basically the lifter is self adjusting anywhere in the range just off zero preload to bottoming out. What I've found is if a lifter is tapping at half a turn, it will tap at a 1/4 turn, 3/4, or a full turn. Only time adding preload to the lifter and having it help is if it is bleeding down too quickly, and most of the time the cause of the noise is something else.

Just start the contact of the screw prior to where you want to end up and you can be right on the 1/2 turn or wherever you want. If I want a half turn I'll start the preload with the wrench positioned at 12:00 and have the screw contact the stud at about 4:00 so things are tight at 6:00.

Hydraulic lifters are very forgiving and that's why Comp just says 1/2 turn, and they don't worry about whether you have 1.5 ratio rockers or 1.65 or 1.72.

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Old 09-15-2020, 06:08 PM
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The math is "not" fine.

Dropping the rocker adjusting nut two threads drops the NUT 0.100 inch. The rocker arm is a lever, the pushrod end of that lever (rocker arm) is moving more than the adjusting nut does; which will vary with the rocker ratio and the specific geometry of the valvetrain.

Except for that, I agree with everything Mick Batson says, above.

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Old 09-15-2020, 06:47 PM
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Ok. Maybe I will just use a feeler gauge to see how much movement there is between the current adjustment and bottoming out the plunger to get a rough idea of where I am at. Take it for a ride, if it still makes noise, take it down another 1/2 turn or so.

I'm not necessarily trying to cure the issue (although that would be nice!), if the noise changes enough for me to be sure that the lifters are the issue then hey, that's progress. Right now it could be anything.

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Old 09-15-2020, 07:46 PM
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Don’t want to hijack this thread but I’ve always wondered .

Can you adjust hyd rollers with the engine running like hyd flat tappets? If not, why is that?

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Old 09-15-2020, 08:17 PM
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Put a dial indicator on the rocker right above the pushrod to measure lifter pushrod cup movement and put your preload exactly where you want it.

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Old 09-16-2020, 10:16 AM
78w72 78w72 is offline
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Quote:
Originally Posted by Murf View Post
Don’t want to hijack this thread but I’ve always wondered .

Can you adjust hyd rollers with the engine running like hyd flat tappets? If not, why is that?

Thanks
Murf


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technically i would say yes but im sure others can confirm that... but doing it with the engine running has always seemed kind of a backyard lazy way to do it & wont always be accurate. i had a friend that used to do that on a sbc & after watching him do it a couple times, (he always thought it ran better each time he changed the adjustment) i determined it was not accurate & each rocker adjustment ended up different than the others. plus all the oil that got all over the engine!

yes you can rig up something to catch most the oil or hope it doesnt pump out past the heads but personally i prefer to adjust each one individually to know its at the right adjustment. or for smaller cams you can do the sbc way of adjusting certain lifters at tdc, then the rest when the engine is rotated to a certain position... common procedure shown in most repair manuals.


Last edited by 78w72; 09-16-2020 at 10:39 AM.
  #11  
Old 09-16-2020, 10:47 AM
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Most of the lifter manufactures recommend setting the preload at 1/2 of the total travel. You don't need a dial indicator to do this but you can use one if you like. Put the lifter at zero lash then bottom it out while counting the number of turns on the poly lock, then back it off 1/2 that amount. When you tighten the set screw hold the poly lock with a wrench so it doesn't move while tightening. Then you end up at the middle of the travel this is not a complicated process. If you still have ticking at this setting then maybe you can live with it as it doesn't necessarily mean there is a problem just a lifter that does not have the best leakdown rate, or get a new set of Johnson Lifters and put them in.

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Old 09-16-2020, 11:57 AM
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I tried the engine running deal and made a mess. Going to cut up some old valve covers and try it again.

I might eventually learn to live with the noise. I have an old truck that ticks like crazy and it doesn't bother me a bit, but with all the $ I've got in this GTO I sometimes let the little stuff get to me. Gotta learn to drive it and not sweat the small stuff.

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Old 09-18-2020, 10:21 PM
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Tim, wouldn't there be a risk of hanging the valve open ? Curious how much preload is total in a lifter?

Comp says this about their website:

Setting Hydraulic Lifter Pre-Load
When installing a hydraulic cam, new hydraulic lifters or rocker arms, it is necessary to establish the
proper lifter pre-load. Insufficient pre-load will cause excessive valve train noise. Too much pre-load
will cause the engine to idle rough or have low manifold vacuum. It is critical to engine efficiency and
to the service life of the valve train for the lifters to have the proper amount of pre-load. On any
hydraulic camshaft, the ideal lifter pre-load is .030” plus or minus .010.”

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Old 09-19-2020, 05:47 PM
Schurkey Schurkey is offline
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Quote:
Originally Posted by kyle_blake View Post
Curious how much preload is total in a lifter?
Varies by lifter; some are limited to a few thousandths of plunger travel, some have as much as a quarter-inch of plunger travel. The only way to be sure is to push the plunger and observe the amount of travel down from the snap ring/wire retainer clip.

Quote:
Originally Posted by kyle_blake View Post
Comp says this about their website:

Setting Hydraulic Lifter Pre-Load
When installing a hydraulic cam, new hydraulic lifters or rocker arms, it is necessary to establish the proper lifter pre-load.
Somewhat true, but given pushrods of different lengths, you've got a range of acceptable preload, not one single distance that's "perfect" and all other preload distances are "wrong".

Quote:
Originally Posted by kyle_blake View Post
Insufficient pre-load will cause excessive valve train noise.
Stated very poorly. As presently stated, this is wrong. Excessive valve train noise comes from having NO preload, specifically "lash"--an actual gap in the valvetrain. This is not "insufficient" preload which implies "some" preload but not "enough".

Quote:
Originally Posted by kyle_blake View Post
Too much pre-load will cause the engine to idle rough or have low manifold vacuum.
Again, stated very poorly. If the "preload" is so great that it makes the "idle rough or have low manifold vacuum", you've gone beyond "preload" so as to have bottomed-out the plunger plus enough extra to hold the valve open. It's the valve being held open that's responsible for the roughness and low vacuum.

Quote:
Originally Posted by kyle_blake View Post
It is critical to engine efficiency and to the service life of the valve train for the lifters to have the proper amount of pre-load.
As long as we accept that with most lifters, there's a range of preload between "enough" and "too much" of perhaps .200", (sometimes less, rarely more) then this statement is true. If they're implying that there's one exact preload amount that's correct--and all other preload distances are "wrong", then this statement is bullshiit. I lean towards "bullshiit" based on their next claim:

Quote:
Originally Posted by kyle_blake View Post
On any hydraulic camshaft, the ideal lifter pre-load is .030” plus or minus .010.”
This is absolutely wrong, and IMPRACTICAL as well. First off, the CAMSHAFT is not what determines proper lifter plunger preload. That'd be the lifters, not the cam.

Pushrods come in shelf-stock increments of .050; so stating that lifter preload has to be at least .020, but not more than .040 is Nucking Futs. What do you do if proper rocker geometry gets you .042 preload? You order the next-shorter "stocked" pushrods, and you've now got .008 lash and a noisy top-end that beats-up the valvetrain.

Some lifters don't have .020 travel, you could not possibly adjust them to .030 preload + or - .010. I got caught with this when I ordered the "recommended upgrade" lifters to go with a Lunati cam I'd bought. There was ZERO mention that the "upgrade" lifters were restricted to a few thousandths of plunger travel--.006 or .010 plunger travel, something like that. I cranked 'em down the usual "half-turn" and as a result I had a dog of an engine.

Overall, this is a huge fail for Comp Cams tech/customer service department.

If you have "some" preload under all operating conditions, the valvetrain should be quiet.
If you don't have "too much" preload under all operating conditions, the valves will close, and the engine will run smooth with manifold vacuum appropriate for the cam grind.

Additionally, you'd want enough preload to accommodate the valvetrain wear during the service life of the engine.

Further, lifter plunger preload will depend on pushrod length and rocker geometry; with rocker geometry being set by design with non-adjustable rockers (shaft rockers, for example, or Pontiac "bottle-stud torque-and-forget" style of individual rockers. But with individually-adjustable rockers, pushrod length affects preload AND rocker geometry, so you get the geometry "right" and--within reason--let the lifter preload fall where it may; anywhere within the plunger travel between "some" and "too much".


Last edited by Schurkey; 09-19-2020 at 06:00 PM.
  #15  
Old 09-21-2020, 08:44 PM
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Kyle Blake

To answer your question every lifter design/type has a different amount of plunger travel, so lifter pre-load requirements would not be the same for all hyd lifters. I don't know about comp lifters although comp cams does not make their own lifters but buy them from lifter manufactures and they change vendors over the years depending on price, reliability and availability. The info I provided was from Johnson Lifter as related to their hyd roller lifters.

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