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GM Hydraulic lifter preload adjustment question

jon_allen

Regular Contributor
Hi All

I have seen different procedures listed for GM hydraulic lifter preload adjustment on this forum.

I tend to go with the 8 stop method.

My question:

Is the two stop method recommended in most GM
service manuals subpar in some way?

Two stops are far easier than 8

Thanks

Misfit
 
.................
Hi All

I have seen different procedures listed for GM hydraulic lifter preload adjustment on this forum.

I tend to go with the 8 stop method.
Jon, the 8 stop procedure (V-8 engines) is more accurate, and it offers lessor chance of a mistake.

Bring #1 piston to TDC on the Compression Stroke.
Adjust the plunger depth for both intake and exhaust while each follower is at bottom of base circle.
Rotate 90* until the next cylinder in the firing order is now at TDC on the compression stroke.
Do the same.
Now rotate another 90* and continue right down the firing order.


My question:

Is the two stop method recommended in most GM service manuals subpar in some way?
In my opinion, yes.

Two stops are far easier than 8
IMO, the 2 or 3 stop is a short cut, and it does not necessarily take any less time.
In some cases, it requires the need to go back through them dynamically.

Thanks

Misfit
 
""Is the two stop method recommended in most GM service manuals subpar in some way?
In my opinion, yes. ""



Of course GM the OEM of the engine recommends a "subpar" procedure.
I wonder if they, GM agree?

So an opinion like this does not belong here as the person expressing it does not have the expertise as compared to GM to offer such an opinion!


Use which ever method you are most comfortable with as they both will achieve the same results if done correctly.
 
...
My question: Is the two stop method recommended in most GM service manuals subpar in some way?
No, think about it....GM emplys humans to create their products...so they are all subject to some errors....do you think if the procedure was inaccurate (or lacking in some other way) that it would have survived 40+ years in their service manuals?
 
IMHO.... If you do several of these procedures a year as a mechanic, then you probably can do a satisfactory job with the two stop, However, if for most who post on this site, this will be the one and only time they will do this in their life, use the 8 stop. In the greater scheme of things for a DIY how much time are you saving and whose time is it doing the 2 stop vs the 8 ??? Based on my experience, MERC ( and most other manufacturers) only do enough to get thru the warranty. It's YOUR engine take the extra time. I've done both ( as an experiment) and found I was more comfortable with what was actually happening in my engine with the 8 stop.

Sooo... if you have a "rate to make" ( and you don't have to live with the results) do the 2 stop... if you have all the time in the world and have to live with the results... do the 8 stop.
 
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Us olde timers use a different method that rarely screws up (especially when you're tired or in a hurry): Take one cylinder at a time, raise the intake to full height and adjust the exhaust valve. Turn the crank until the exhaust valve is full open and adjust the intake, then go to the next cylinder. (It helps if the plugs are out.)

Jeff
 
Bob said:
IMHO.... If you do several of these procedures a year as a mechanic, then you probably can do a satisfactory job with the two stop, However, if for most who post on this site, this will be the one and only time they will do this in their life, use the 8 stop. In the greater scheme of things for a DIY how much time are you saving and whose time is it doing the 2 stop vs the 8 ??? Based on my experience, MERC ( and most other manufacturers) only do enough to get thru the warranty. It's YOUR engine take the extra time.
I've done both ( as an experiment) and found I was more comfortable with what was actually happening in my engine with the 8 stop.


Sooo... if you have a "rate to make" ( and you don't have to live with the results) do the 2 stop... if you have all the time in the world and have to live with the results... do the 8 stop.

Bob, well said. You and I are willing to think out-side-of-the-box, whereas the younger guys, who view the manual as the gospel, are more prone to staying within the box.


Jon, you said earlier; "I tend to go with the 8 stop method", and I think that is wise.
With your best interest in mind, I'm going to elaborate on this for you:



SBC V-8 with hydraulic cam followers (aka lifters).
Firing order is 1-8-4-3-6-5-7-2.
The goal..... set the depth of the cam follower's hydraulic plunger.

hydraulic cam follower cut view.jpg

Mark off your harmonic balancer in increments of 90* from the TDC marking.
Remove all spark plugs.
Bring #1 piston up to TDC on Compression stroke. Must be on the C/S!
(both followers are within bottom of base circle..... just where we want them to be)

hydraulic cam follower at bottom of base circle.jpg

Adjust both intake and exhaust rocker arm nuts as to find ZERO valve-stem-to-rocker-arm lash.
Further adjust both rocker arm nuts until the push rod sets the cam follower plunger to the prescribed depth.
(there is approximately .100"+ total plunger travel.... the math takes this to around .040" or so plunger depth)

Next..... roll crank 90*.
Do same to #8.

Roll crank another 90*.
Do same to #4.

Roll crank another 90* and repeat and continue right on down the firing order.

It may take you 2 or 3 minutes longer to use the 8 stop. However, it ensures that the followers are within bottom of base circle, and it reduces the likelihood of any errors that may occur with the 2 or 3 stop method.
When used correctly, you will not need to go back through them dynamically!


I have been using the 8 stop method since around 1965 or so. It has never failed me nor anyone who I have shown it to.

I have never used the 2 or 3 stop method because I could see that it is not nearly as accurate.


.
 
WTF dude....Another waste of space.........

PCR at it again.........

2x

Marine Lifter adjustment..... Simple........ Pick a cylinder, turn crank, watch rockers, When one moves to max lift adjust the other... To zero Lash (don't use the "spin the push rod" method) just wiggle the rocker up and down until all play between the valve and rocker is gone... Once you have this, tighten the rocker nut 1/2 turn.... No more. Now do the other rocker on that cylinder....Done.... Move on to the next cylinder...

No one is going to measure plunger depth movement.
 
No one is going to measure plunger depth movement.

Chris, you are absolutely correct! No one is going to measure it, nor is there a need to measure it.
The 1/2 turn (past ZERO lash) that you yourself just explained, sets the plunger depth for us.
Personally, I favor 3/4 turn for a 1.5:1 rocker arm ratio, and yes.... I have done the math!


 
Chris, you are absolutely correct! No one is going to measure it, nor is there a need to measure it.
The 1/2 turn (past ZERO lash) that you yourself just explained, sets the plunger depth for us.
Personally, I favor 3/4 turn for a 1.5:1 rocker arm ratio, and yes.... I have done the math!




it is totally unrelated to the post question. You, Math...........Now that's some funny SH!T!
PCR at it again.........
 
.."Marine Lifter adjustment..... Simple........ Pick a cylinder, turn crank, watch rockers, When one moves to max lift adjust the other... "

That's her.

Jeff
 
I did it with the 2 step method in both GM shop manuals and my OMC shop manuals, first time, and no problems at all. Just pay attention to what you are doing, mark the intake and exhaust valves, not rocket science. When I fired it up after the top end overhaul it sounded exactly the same as it always had before. No odd noises, 160-170 comp test results....
 
I did it with the 2 step method in both GM shop manuals and my OMC shop manuals, first time, and no problems at all. Just pay attention to what you are doing, mark the intake and exhaust valves, not rocket science. When I fired it up after the top end overhaul it sounded exactly the same as it always had before. No odd noises, 160-170 comp test results....

Based on PCR's POST

1. """I tend to go with the 8 stop method", and I think that is wise. ""


Is the two stop method recommended in most GM service manuals subpar in some way?

2. """In my opinion, yes."""

3. ""
I have done the math!""


You are unwise...............................................and used a SUBPAR method.........But I bet you did NOT do the MATH...............Or stay at a Holiday Express last night.
 
One tip I did pick up...determine zero lash by lifting the pushrod up and down and tightening the rocker arm nut just until you can’t lift it up and down instead of tightening the rocker arm nut till you can’t spin it with your fingers seems more accurate. In fact I think the accurate determination of zero lash is actually more important than which way you use to adjust the hydraulic lifters....because if you use the spin the pushrod method, there is a good chance you are going to get them too tight no matter if you use the 2 stop, 8 stop or whatever way you do it...
 
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Be careful when you post your experience and or preferred methods.

Remember,There is only ONE!

PCR may respond with a mile long post detailing the minutia of how the earth was created and how HE and only HE was there to witness it and thus is the ALL knowing "EXPERT" on all things Marine and GM engines.............

If he does it will take a month of Sundays to read through it all completely with multi-colored paragraphs and possibly graphics dating back to the steam engine for your confusing pleasure with not one specific OP answer.
 
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Be careful when you post your experience and or preferred methods.

Remember,There is only ONE!

PCR may respond with a mile long post detailing the minutia of how the earth was created and how HE and only HE was there to witness it and thus is the ALL knowing "EXPERT" on all things Marine and GM engines.............

If he does it will take a month of Sundays to read through it all completely with multi-colored paragraphs and possibly graphics dating back to the steam engine for your confusing pleasure with not one specific OP answer.
Now that is funny.
 
Warning:
For those who are not able to read and comprehend more then 10 paragraphs, and/or are not able to decipher images, please ignore this and go to the next post!
:D


(I'm just poking a bit of fun back towards Jack...... most of you guys do not have a problem like that.)

............
One tip I did pick up...determine zero lash by lifting the pushrod up and down and tightening the rocker arm nut just until you can’t lift it up and down instead of tightening the rocker arm nut till you can’t spin it with your fingers seems more accurate.
Louc, that is preferred by many, because the push rod may still spin even while the lash is a bit tighter than ZERO.
See Chris's post #10.

In fact I think the accurate determination of zero lash is actually more important than which way you use to adjust the hydraulic lifters....because if you use the spin the pushrod method, there is a good chance you are going to get them too tight no matter if you use the 2 stop, 8 stop or whatever way you do it...
Louc, as you know, the goal is to set the plunger depth to the OEM specs. Most specs call for the plunger to be set at an average depth of .040" from the upper limit of it's travel. Some even call for .060" MAX.

We also want to make this adjustment while the follower is at/near bottom of base circle.
The 8 stop procedure ensures this.

As for the math, it's relatively simple.

If your rocker arm adjustment stud/nut is 7/16" NF, that's 20 threads per inch.
1 nut revolution pushes the rocker arm ball swivel down 1/20"..... or .050".
1/2 nut revolution pushes the rocker arm ball swivel down 1/40" ..... or .025".

Now the 1:1.5 rocker arm ratio must be factored in.
When factored, you'll see that 1/2 turn sets the plunger at around .020" or so.

That is only .020" away from the plunger topping out.


If your rocker arm adjustment stud/nut is 3/8" NF, that's 24 threads per inch.
1 nut revolution pushes the rocker arm ball swivel down 1/24" ..... or .042".
1/2 nut revolution pushes the rocker arm ball swivel down 1/48" ..... or .021".

Now factor in the 1:1.5 rocker arm ratio, and you'll see that 1/2 turn sets the plunger at less than .020" away from the plunger topping out.







The upper image below is from Century Performance.
Look closely at the notation regarding the dimension for what they refer to as "pre-load".
This pre-load is actually in reference to the plunger's depth.

Understand that with a pre-load of .020", the plunger still has an approximate .080" remaining travel.


SBC Cam Follower.jpg






For those Hell Bent on using the 2 stop, here's what you will do:

While at #1 TDC C/S, you will make the cam follower plunger depth adjustments to the rockers arms shown in black.

valve6.jpg



Next, bring #6 around to TDC C/S and adjust the ones shown in red.





If you would like to use the 8 stop, here's what you will do:

SBC 8 stop procedure.jpg



It's your call.





.
 
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When you're in the bilge, trying to do this while not stepping on something or bashing your head on the overhead, it's easy to make a mistake with the "two step" (at first, then a bunch more later after you screw up).

Take your pick.

Jeff
 
Warning:
For those who are not able to read and comprehend more then 10 paragraphs, and/or are not able to decipher images, please ignore this and go to the next post!
:D


(I'm just poking a bit of fun back towards Jack...... most of you guys do not have a problem like that.)

............


As for the math, it's relatively simple.

If your rocker arm adjustment stud/nut is 7/16" NF, that's 20 threads per inch.
1 nut revolution pushes the rocker arm ball swivel down 1/20"..... or .050".
1/2 nut revolution pushes the rocker arm ball swivel down 1/40" ..... or .025".

Now the 1:1.5 rocker arm ratio must be factored in.
When factored, you'll see that 1/2 turn sets the plunger at around .020" or so.

That is only .020" away from the plunger topping out.


If your rocker arm adjustment stud/nut is 3/8" NF, that's 24 threads per inch.
1 nut revolution pushes the rocker arm ball swivel down 1/24" ..... or .042".
1/2 nut revolution pushes the rocker arm ball swivel down 1/48" ..... or .021".

Now factor in the 1:1.5 rocker arm ratio, and you'll see that 1/2 turn sets the plunger at less than .020" away from the plunger topping out.







The upper image below is from Century Performance.
Look closely at the notation regarding the dimension for what they refer to as "pre-load".
This pre-load is actually in reference to the plunger's depth.

Understand that with a pre-load of .020", the plunger still has an approximate .080" remaining travel.


View attachment 22938






For those Hell Bent on using the 2 stop, here's what you will do:

While at #1 TDC C/S, you will make the cam follower plunger depth adjustments to the rockers arms shown in black.

valve6.jpg



Next, bring #6 around to TDC C/S and adjust the ones shown in red.





If you would like to use the 8 stop, here's what you will do:

View attachment 22939



It's your call.





.

On the traditional small-block Chevy, everyone learned at a tender age about ...
The total piston travel in the lifter plunger is roughly 0.120- to 0.150-inch for standard non LS models


LS models are greater .200" to .210".

WRONG AGAIN!
 
..............

On the traditional small-block Chevy, everyone learned at a tender age about ...
The total piston travel in the lifter plunger is roughly 0.120- to 0.150-inch for standard non LS models

There is NO piston travel in the lifter plunger. The Plunger/Piston are one-in-the-same!
Some refer to this as a piston, some refer to this as a plunger. It is the same part of a hydraulic cam follower (aka Lifter).
This part (the plunger or piston) travels within the cam follower body!



LS models are greater .200" to .210".
If that is FACT for the SBC engine, and there is considerably MORE than .100" travel, that's all the more reason for setting the piston/plunger depth closer to .040"!







https://golenengineservice.com/blog/morel-hydraulic-roller-lifter-adjustment-procedure/

Street Performance
CHEVY ENGINES These lifters have .120″ plunger travel and have an 80% fill rate with the test oil.

Performance

These lifters have a .120″ plunger travel and have an 80% fill rate with the test oil.

Hi-RPM Series:
These lifters have a 7000 rpm + capability with a .120″ plunger travel and have an 80% fill rate with the test oil.


This article was written by John Callies, Inc.
Granted, this is not for Marine, but you can certainly understand the basic principle.


Adjusting the Zero-lash setting of the lifter:

  1. I always like using the firing order to set the valves. Put the engine on #1 cylinder.
  2. What we want is the Intake and Exhaust to be on the base circle of the camshaft
  3. Adjust the rocker until the push rod just starts to get tight while taking the pushrod and rolling it between your thumb and finger. Once you feel drag, this is what we call Zero-lash ........ We have discussed that this is not the best scenario.
  4. You are now ready to tighten down on the adjuster using the following method:

  • It is important to know the thread pitch, in threads per inch, of the adjuster nut, because one complete turn of the nut will move a distance of one complete thread. Therefore, verify the thread pitch of the adjuster nut, because racing rocker manufactures use different nut sizes and thread pitches.
  • If your adjuster nut is 7/16×20 threads per inch, then divide 1 inch by 20 threads per inch. One complete turn down on a 7/16 x 20 adjuster nut will move .050″
  • Next, divide .050″ divide by 4 to calculate the distance for a quarter-turn of the adjuster nut (.050″ / 4 = .0125″)
  • For a 3/8 x24 adjuster nut, the caculations are: 1″ / 24 TPI = .042″ per full turn and .042″ / 4 = .0105″ per quarter turn.
  • Use the chart below to determine how many quarter turns to tighten the adjuster nut after Zero Lash
Cast Iron Block and Cast Iron Head = .020″-.025″
Cast Iron Block and Aluminum Heads = .030″-.035″
Aluminum Block and Aluminum head = .045″-.050″

5. Repeat these adjustments for each cylinder running through the firing order.


John has just described the 8 stop procedure.




Here is another article by Gwantney Performance that you may want to read.

https://gwatneyperformance.com/lifters-lash-preload-dont-know-wont-hurt-will/




We all know who Jeff Smith is. If you don't, take a few minutes and read this article by Jeff.

https://www.hotrod.com/articles/ccrp-1109-hydraulic-lifter-install-solid-roller-power/

Jeff confirms the SBC plunger travel of .120" and confirms an average pre-load of .040".



.
 
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be careful when you post your experience and or preferred methods.

Remember,there is only one!

Pcr may respond with a mile long post detailing the minutia of how the earth was created and how he and only he was there to witness it and thus is the all knowing "expert" on all things marine and gm engines.............

If he does it will take a month of sundays to read through it all completely with multi-colored paragraphs and possibly graphics dating back to the steam engine for your confusing pleasure with not one specific op answer.



















I Rest my case!!
 
Where is top of base circle?

attachment.php
Right on Jack.




What you say? Be careful...............you will get a full novel description now..........Just when the post was to end, again in shame...A full multicolored explanation on BC, LSA, LIFTER, PLUNGER, The square root of Pi, Why the earth is flat and why Bernie Bro's are the best!
 
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Fortunately, the "Page Down" button allows me to go past posts I'm not particularly interested in and the criticisms thereof.... : -)
 
What's wrong with the running engine method? I've used it for years on my GM's with no trouble whatsoever.

Agreed, But if you read through the PCR posts you would want to HANG yourself by the neck.......high high quality PCR rope otherwise you would get a encyclopedia's worth of SPEW

TMI.......TMI....................TMI.........
 
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