'91 L98 Coupe.

Note: My first time valve adjustment.

OK, I'm trying to install my stamped steel rocker arms. I'm following the EO-IC (Exhaust Opening, Intake Closing) method to adjust each valve. I think I'm finding zero lash (twist pushrod until you feel resistence). I then turn self-locking nut an extra 360 degrees (according to GM service manual).

Here's the deal, the self-locking nut still feels loose. I would expect to feel something like 10-15 ft-lbs of torque, but it's not. I can easily back off the nut. I feel there is not enough torque to keep the rocker arm in place.

Is this how it suppose to feel? Should the rocker arm wiggle after tightening? When removing them I remember needing to muscle these nuts off.

By the way, these are new rocker arms and nuts (CompCams) being installed. I'm not using any old parts.

Thanks for any help.

 

If you search in the Tech section, using Advanced, Archives, there are alot of posts on tech tips and info concerning this.

 

ok, if the nuts feel loose, you might ned to replace them.
Here's how I do the adjustment........
1. put the engine on TDC. both #1 rockers will be loose. adjust the rockers till you feel them sort of tighten and they don't wiggle as much. tighten them 1/4 turn more. Then have an assistant click the engine over to the next cylinder to fire. 1-8-4-3-6-5-7-2
2. adjust it at the tdc for that cylinder, and the rockers will be loose. tighten till they sort of do the same.
If you let them sit, they will loosen up to sloppy again as the lifters bleed down a little.
get them all adjusted like that, cover the areas adjacent to the rockers, and start it up.
loosen each rocker till it clacks, then tighten till they stop clacking, then tighten 1/4 to half turn.
do them all. you can use an old tin rocker cover with no baffles in it to adjust one sice and cover the other side to eliminate some of the mess.
Rocker adjustment isn't fun because of how many things you have to loosen, but it's fun when everything works to the good.
If you were to buy roller rockers, they control the upper engine oil a lot better, and there's no squirting. It's amazing how nice and even the oil flows out of them when you adjust the rockers with them. With full roller rockers, you get a 5-10 PSI oil pressure boost because they control the oil, and keep the oil pressure from squirting out all over the place.
You can even upgrade to 1.6 rockers, and no mess, and a little punch to boot.

 

1/4 turn of preload is all you need....the hydrolic lifter's push rod seats ride on a cushion of oil when the car is running....they will seem loose but once oil pressure is applied...poof....they're good to go.
Only tighten each rocker nut once after "0" lash (spin the pushrod and tighten 'til it almost stops spinning and gets tight--then give it a 1/4 turn more) follow the correct order for the cam/crank position....some rockers may seem loose but don't worry about it.

The "old" style solid lifters were a pain in the a$$ they did not have the internal oil cushion and you had to stay on top of the gaps with a feeler gage quite often.......Your roller hydroic lifters are a fairly maintenance free set up once the adjustments are done correctly the first time.

 

Thanks for the tips. I did search the forum and found lots of info on how to adjust, but really didn't get a sense for the 'Feel' of zero lash.

Well I found a sure fire way of finding zero lash without the 'feel' part. The only problem is your intake manifold must be removed. No problem for my build since it was already off.

This is how:

1) Choose your favorite method of starting valve adjustment. some like to do the TDC on each cylinder and adjust both the valves for that cylinder. Others prefer to EO-IC method (exhaust just opening, adjust that cylinders intake. Intake 3/4 closing, adjust that cylinder's exhaust). And the GM FSM method is to find TDC on cylinder #1. Then adjust exhaust valves 1,3,4,8 and intake valves 1,2,5,7. Then turn crank 360 degrees to cylinder #6 TDC. Then adjust exhaust valves 2,5,6,7 and intake valves 3,4,6,8.

2) Loosen the adjuster nut until there is play with the Pushrod. Grapse the pushrod and pull it upwards against the rocker arm until the rod and rocker arm is firm against the valve. This will lift the pushrod off the lifter.

3) With a socket and extension, hand tighten the adjuster nut until the pushrod makes contact with the lifter. This is zero lash. You can tell if you go too far because you will see the spring go down on top of the lifter.

4) After you find zero lash, tighten anywhere between 1/4 to 1 turn depending upon your situation. Performance guys tend to do 1/4 to 1/2 turn. Stock/street tend to go 3/4 to 1 because that's what GM recommends.

I guess this can be done with the intake manifold in place. You should be able to see the lifter through the pushrod guideplates using a flashlight. There may be too much oil puddled around the lifter though.

Anyway, just another method of finding zero lash to add to the archives so the next newb will try and search and not find and repost the question all over again and we all get to re-explain the techniques.

Such is the life of forums!

 

A good way to be sure when you are at zero lash is to "jiggle" the push rod up and down, rather than twisting it, as you tighten the adjusting nut. When the "jiggling" just barely stops, you are at zero lash.

The amount of preload, 1/4 turn vs 1 whole turn, is not critical, unless you are trying to establish the minimum preload to minimize the effects of lifter pump up for an extra 100 to 200 rpms. A 1/4 turn, a full turn, and anywhere in between, are all as good as the other.

When you add preload, you are not compressing the valve spring, only the small plunger spring inside of the lifter. You won't feel any significant increase in the torque required to turn the adjusting nut as you set the preload. If the self locking nuts used with stamped steel rockers are too easy to turn, they need to be replaced.

RACE ON!!!

 

w/this in mind I have a question: On a typical sbc lifter what is the max. amount of travel in the plunger ?

 

I have never checked. One turn of the nut on a 3/8" - 24 threaded stud is ~.042". I'd have to guess there is an 1/8" or more plunger travel.

RACE ON!!!

 

Some of the aftermarket rocker adjustment nuts have an allen lock screw in the top. If it is the mechanical crimped style lock nut, it should be tight as soon as the top of the nut starts down onto the stud. I agree with the others, if it is not tight, replace them.

 

thanx... I asked that question because I had once thought there may be only a total of .128. I like the idea of using the 24 thread as a method to create a real number of pre-load. I had never considered that before you mentioned it. When I first did mine I put an indicater on the plunger to understand amount of turn (1/4-1/2 etc.)vs. what a .030 preload equals (comp cams recomendation for pre-load).

 

The "an 1/8" or more plunger travel", I guessed is only, .125", very similar to "a total of .128". But like I said, I don't know. I'm only guessing.



With a 7/16" stud, the fine thread (adjusting nut end) of the stud is 7/16 - 20. Therefore, 1.000" ÷ 20 = .050", nut travel (preload) per turn.

RACE ON!!!

 

OK experts I need your opinion:

When I hit zero lash, I can tighten up to one complete turn of the lock nut by hand using only a socket with an extension on it. No rachet needed. These nuts are new and came with the rockers.

Should I get new locking nuts??

 

if it was me, yes I would get the nuts that have the allen screw on top to lock them. having your rockers loosen up on you once you get it dialed in is going to make you pull your hair out and punch your self in the face over and over. they are only like $30 - $50 but they are re usable for a real long time.
im definately ordering a set of the polly locks when its time for me to switch over to some comp 1.6 roller tips.

 

if you can turn lock nuts by hand, throw them away and buy new ones.
Although, I have resurected a few lock nuts (none inside an engine) by using a hammer and a punch on the lock crimps.
Just thread the nut on a disposable bolt 1/3 the nut thickness, and punch the crimp triangles. you will notice that they get progressively harder to turn if you do all three crimps.
Like I said, if you use these nuts in an engine, you are nuts.

 

your lock nuts are definately bad. the more you tighten and loosen them the less effective they are. get new ones.

 

That's what I thought. Thanks for the tips.

 

Are these self locking nuts, like the stock nuts? Or are they the adjusting nut portion of a poly lock? As I said above, adjusting the preload should not make the nut any harder to turn. You are only compressing the lifter plunger spring. A self locking nut should be difficult to turn as soon as the stud is all the way through the nut, long before zero lash is reached.

RACE ON!!!

 

Make sure the rockers are self centering - for roller cam lifters. Solid tappet rockers will not adjust correctly - they tend to "cam" off to one side or the other, changing the clearance.

 

Self aligning rockers have nothing to do with the type of lifter used, flat tappet, roller, solid or hydraulic. Chevy used three methods of keeping the rocker tip centered over the valve stem. It is a matter of the way the head is made and what hardware is used. It has nothing to do with the lifters used. Any of the three methods can be used with any lifter. But never use more than one of the three methods in any given engine. They could cause interference with one another. Also, none of the alignment methods will cause problems with hydraulic lifter preload or cause self locking nuts to not self lock. Other than that...good post.

RACE ON!!!

 

[QUOTE=CFI-EFI;1561857452]Are these self locking nuts, like the stock nuts? Or are they the adjusting nut portion of a poly lock? As I said above, adjusting the preload should not make the nut any harder to turn. You are only compressing the lifter plunger spring. A self locking nut should be difficult to turn as soon as the stud is all the way through the nut, long before zero lash is reached.

These are self-locking nuts. They are not hard to turn at all. I'm replacing them with polylocks. That way I'm in control.