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New Magnum rockers comp 1621-16

Ronald Weishaar

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Just got these rockers for my 540 cu. in .557 lift cam. I got the adj pushrods and soft valve springs from comp. Just spent all day trying to get the correct pushrod length with no luck. Can someone help with a sure fire way of doing this task? I look on you tube for help and all you see is bowtie instructions that say this applies to all v-8's.
 
I think you have to have a solid lifter, I went through 2 differnet checkers before getting mine right.
What cam type and what did you come up as a measurement?
 
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It’s very simple.

-Install adjuster screw into rocker arm as far as it will go
-turn adjuster screw down one full turn.
Snug lock nut.
-with cam on base circle, and rockers snugged onto head, set checking pushrod length to take up all the slack in valvetrain.
It’s best to have correct thickness feeler gauge between roller and valve tip.
-remove rockers from head, measure length of checking tool/pushrod.
-Order that length pushrods.

No need at all for the soft springs.
In fact it’s easier if you’re not using them.
 
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-Install adjuster screw into rocker arm as far as it will go
-turn adjuster screw down one full turn.
Snug lock nut.

This is confusing IMHO. If I turned my screws down as far as they'd go they'd go right out the other side.

Turn the screw in till there are two threads showing above the pushrod. Tighten the nut. Install and adjust the checker pushrod.

I think the idea of the soft spring is so you can depress the valve to remove the pushrod and determine it's length. Otherwise, you need to remove the whole shaft to get the pushrod(s) out.

You have the heads on with the gaskets, right?
 
I will say this , I have the Comp ProMags and one thing I noticed is that the oil pasage is really low on the adjuster.
I did mine the first time like Stanton is saying, but will do it like PR Heads is saying this time.
I was really worried about exposing the oil galley with two threads showing then a full turn for 0 lash ( hydraulic lifters).
While parts cleaning I checked to see how many threads I could show on the bottom before flow was affected from the rocker journal through the adjuster and possibly expose the oil galley.
It was about 3 threads and around 2 1/2 it appeared the flow was restricted somewhat at journal.
I was taking the parts washer nozzle and force feeding the solvent back through the adjuster and made it back flow into the rocker arm.

If none of this makes sense pull the adjuster completely out and verify its (oil passage) position realtive to the length of the stud and compare it to how many threads are between the bottom of the rocker and the oil pass in the rocker.
 
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I will say this , I have the Comp ProMags and one thing I noticed is that the oil pasage is really low on the adjuster.
I did mine the first time like Stanton is saying, but will do it like PR Heads is saying thos time.
I was really worried about exposing the oil galley with two threads showing then a full turn for 0 lash ( hydraulic lifters).
While parts cleaning I checked to see how many threads I could show on the bottom before flow was affected from the rocker journal through the adjuster and possibly expose the oil galley.
It was about threads and around 2 1/2 it appeared the flow was restricted somewhat at journal.
I was taking the parts washer nozzle and force feeding the solvent back through the adjuster and made it back flow into the rocker arm.

If none of this makes sense pull the adjuster completely out and verify its (oil passage) position realtive to the length of the stud and compare it to how many threads are between the bottom of the rocker and the oil pass in the rocker.
It's still as clear as mud! Do you start with the cam on compression TDC? Do you set adj pushrod at zero lash? Do you need to check for contact of roller tip on valve stem? Did not know there was an oil passage on the rocker adjustment tip! And that the amount of thread showing would restrict that oil flow! .557 cam is a solid lifter cam
 
It's still as clear as mud! Do you start with the cam on compression TDC? Do you set adj pushrod at zero lash? Do you need to check for contact of roller tip on valve stem? Did not know there was an oil passage on the rocker adjustment tip! And that the amount of thread showing would restrict that oil flow! .557 cam is a solid lifter cam
Yes, I think a solid is the same measurement process and you are using checking springs & yes, I used this table for the adjustment.
As far as checking the sweep I did an initial base check and after final install. Everything was pretty much spot on.
Attached is a pic of a rocker that shows where the oil flows. Also attached is a pic of the adjuster so you can see how the oil flows through it for the push rod.
Others may have a different process, and I'm not a pro either!

BBM-Mopar-Valve-Lash-Adjustment-Chart-607x607.jpg Screenshot_20210822-061747_kindlephoto-2076073909.png Screenshot_20210822-063004.png
 
Ok, let's back up.
FIRST - forget the above chart, you're not there yet.

From Mr. Porter's reply:

Install adjuster screw into rocker arm as far as it will go
-turn adjuster screw down one full turn.


to clarify this, you have a "cup" style adjuster. Screw it in from the bottom as far as it will go then back out one full turn.

Snug lock nut.

Do you start with the cam on compression TDC?

Forget this, just get the lifter you're measuring on the base circle of that lobe.

-with cam on base circle, and rockers snugged onto head, set checking pushrod length to take up all the slack in valvetrain.

Do you set adj pushrod at zero lash?

It’s best to have correct thickness feeler gauge between roller and valve tip. YES, THIS IS YOUR LASH !!

-remove rockers from head, measure length of checking tool/pushrod.
-Order that length pushrods.

Do you need to check for contact of roller tip on valve stem?

Huh ?!?! Of course you want the roller to contact the valve tip !!!

And FWIW, you say you got adjustable "pushrods". You only need ONE and you only need to measure ONE. The rest will all be the same. If they're not, you have bigger problems !!

Hope this helps.
 
If you do exactly the steps I outlined, you’ll end up with the correct length pushrods.
Those instructions are for a solid cam, which is where the use of the feeler gauge comes into play.

These instructions are only for shaft mounted rockers with cup style adjusters, that oil through the adjuster, that cannot be screwed “through” the rocker arm....... all of this is applicable to the Comp 1621-16.
**The old “number of threads showing under the rocker” technique does not apply to these rockers**

There is an oil band on the adjuster screw that must line up with the oil feed hole in the rocker body.
The range of adjustment for that to happen is a nominal zero turns out.......to......two turns out.
One turn from seated is the mid point.

On these rockers, the adjuster screw is installed from the bottom:

0CBC8D29-C418-46AD-9AB6-A400B29EED99.jpeg

Screw it in all the way till it stops:

A33D8178-CCC7-45D2-99B6-0EFBE34D4FD2.jpeg

Screw it back down one full turn, install lock nut, snug it down:

E47D49C8-11A8-4263-8AC8-FF4992F2F84C.jpeg

Install rocker on shaft, snug shaft down on head.
With cam on base circle(lifter as low as it can go), and checking pushrod in place...... adjust the length of pushrod/tool to eliminate all slack in the valvetrain.
If it’s a solid cam, have the correct thickness feeler gauge between the roller and the valve tip(the same thickness as what you use to set the valve lash).
**if you don’t use the checking spring, when the checking tool reaches the correct length, it will be hard to extend it any farther.
With checking springs, extending it too far will just start to open the valve.
I prefer to use the regular spring for the more positive feel when you’ve eliminated all the slack**

Remove the rocker from head, remove checking tool(being careful not to upset the adjusted length).
Measure tool. That’s the length of pushrods needed.

That’s all there is to it. 19F0738C-5DBE-46C3-9D59-F8F0869CD0EB.jpeg
 
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What I do for hyd cams is:
All the steps are the same, but you don’t use the feeler gauge, and you have to be very careful not to compress the plunger in the lifter.
I shoot for just barely a “zero” preload.

Then, after you measure the tool, add to that length however much lifter preload you desire.

So for example, if the tool measured 9.120”, and I wanted .030” preload, I’d order pushrods that were 9.150”.
That way with the adjuster set in the middle of the range, I’d have the lifter set at the desired preload.
 
What I do for hyd cams is:
All the steps are the same, but you don’t use the feeler gauge, and you have to be very careful not to compress the plunger in the lifter.
I shoot for just barely a “zero” preload.

Then, after you measure the tool, add to that length however much lifter preload you desire.

So for example, if the tool measured 9.120”, and I wanted .030” preload, I’d order pushrods that were 9.150”.
That way with the adjuster set in the middle of the range, I’d have the lifter set at the desired preload.
Thank you all for your explanations. Don't know how it got so confusing! I feel a lot better knowing the oiling system in theses rockers.
 
If you do exactly the steps I outlined, you’ll end up with the correct length pushrods.
Those instructions are for a solid cam, which is where the use of the feeler gauge comes into play.

These instructions are only for shaft mounted rockers with cup style adjusters, that oil through the adjuster, that cannot be screwed “through” the rocker arm....... all of this is applicable to the Comp 1621-16.
**The old “number of threads showing under the rocker” technique does not apply to these rockers**

There is an oil band on the adjuster screw that must line up with the oil feed hole in the rocker body.
The range of adjustment for that to happen is a nominal zero turns out.......to......two turns out.
One turn from seated is the mid point.

On these rockers, the adjuster screw is installed from the bottom:

View attachment 1156013

Screw it in all the way till it stops:

View attachment 1156014

Screw it back down one full turn, install lock nut, snug it down:

View attachment 1156015

Install rocker on shaft, snug shaft down on head.
With cam on base circle(lifter as low as it can go), and checking pushrod in place...... adjust the length of pushrod/tool to eliminate all slack in the valvetrain.
If it’s a solid cam, have the correct thickness feeler gauge between the roller and the valve tip(the same thickness as what you use to set the valve lash).
**if you don’t use the checking spring, when the checking tool reaches the correct length, it will be hard to extend it any farther.
With checking springs, extending it too far will just start to open the valve.
I prefer to use the regular spring for the more positive feel when you’ve eliminated all the slack**

Remove the rocker from head, remove checking tool(being careful not to upset the adjusted length).
Measure tool. That’s the length of pushrods needed.

That’s all there is to it. View attachment 1156050
What I do for hyd cams is:
All the steps are the same, but you don’t use the feeler gauge, and you have to be very careful not to compress the plunger in the lifter.
I shoot for just barely a “zero” preload.

Then, after you measure the tool, add to that length however much lifter preload you desire.

So for example, if the tool measured 9.120”, and I wanted .030” preload, I’d order pushrods that were 9.150”.
That way with the adjuster set in the middle of the range, I’d have the lifter set at the desired preload.

There are a few people who should be paid for posting here............this is one of them.
 
Perfect explanation for these rockers, I alway confuse people. Thanks!
 
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