Rocker arm adjustments

[Big Paul]

How do you adjust rocker arms on a rebuilt engine without it running first ? without any problems of it starting right up....

 

[MrMarty51]

Engine thoroughly warmed up.
Number one on TDC
Adjust:
Exhaust:1-3-4-8
Intake:1-2-5-7
Number six TDC
Adjust:
Exhaust:2-5-6-7
Intake:3-4-6-8

 

[Big Paul]

Mr Marty I thank you !

 

[MrMarty51]

Mr Marty I thank you !

Not a problem,You adjust them to zero lash + one turn,If You are not familiar with zero lash that is when any cleareance between the lifter and rocker arm is removed,it is felt by moving the push rod betrween the two components and when any up/down movement is adjusted out that is zero clearance.
If the engine is cold then go ahead and adjust them by this method and that`ll get it close enough to start then the lifters can be adjusted with the engine running after it has come to operating temp.
A set of those handy dandy clips on the rockers helps to keep the splatter down a bit,quite a bit.they do`nt cost much at the parts store.
A nice splash and squirt deflector can be made if You have a spare set,or one single rocker cover and cut it out on the lower half of the top flat so that You can get the wrench onto the rockers but the oiling end has the cover over it.

 

[bucket]

I always do zero lash+ 2/3 turn.

 

[MrMarty51]

Yeah,it seems that some books says a half a turn,another says 3/4 turn but if Mine memorie serves Me correctly,which most the times it does`nt,I thinking the GM books most all says a full turn,so,pick Your number,if it works for You then that is exactly how I would doit,do not try fixing something whut aint broke.LOL

 

[chengny]

Whatever pre-load you use (1/2 turn, 3/4 turn, etc) isn't really that critical. It's just to make sure that you have eliminated any lash.

Just be aware that this can only be done one time.

In other words, you can't set your pre-load and then go back around the rockers to "check your work".

If you have any doubts that you pre-loaded correctly, and want to do it again, you'll have to start fresh.

Back the rocker nuts off at least one full turn from where you were. Then walk away and wait an hour or so. That will allow the plunger spring to drive the plunger back up to the top of it's stroke.

Zero lash can only be determined when the plunger is at the very top. When it is at the top there should be no gap between the cup/socket and the circlip.

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[MrMarty51]

After the engine is started and running the lifters can be adjusted by backing the nuts off,one at a time,until a slight tick can be heard,then,turn them down until the tick is just gone,then,give them the additional one full turn then they will then be properly adjusted.

 

[bucket]

Whatever pre-load you use (1/2 turn, 3/4 turn, etc) isn't really that critical. It's just to make sure that you have eliminated any lash.

Just be aware that this can only be done one time.

In other words, you can't set your pre-load and then go back around the rockers to "check your work".

If you have any doubts that you pre-loaded correctly, and want to do it again, you'll have to start fresh.

Back the rocker nuts off at least one full turn from where you were. Then walk away and wait an hour or so. That will allow the plunger spring to drive the plunger back up to the top of it's stroke.

Zero lash can only be determined when the plunger is at the very top. When it is at the top there should be no gap between the cup/socket and the circlip.

That's a good point, I've never thought about that before. How do you feel about pre-soaking new lifters in oil for a couple days? I was always told that's how it's done, but more recently I've heard it's not necessary. I still pre-soak them.

 

[chengny]

I don't pre-soak. I give them a quick shot of WD-40 and check the plunger/spring for freedom of motion - using a pencil eraser and just a slight push. If they bounce, I drop them in and lightly assemble the rods/rockers.

Then I prelube the engine. I always put heat lamps under the oilpan for a couple of hours prior to prelubing. It helps the oil flow throughout the entire system (including the lifter internals) and also makes it easier to hold the drill motor while doing the pre-lube.

Then the lifters are warm, primed and ready to pre-load. And, because they have not been pushed down, the plungers should be at full stroke. I just use the twist rod till resistance is felt and then another 1/2 turn method.

Here is a trick you can use (if the intake manifold is off) to check your work without touching the rocker nuts again:

When you are all done setting pre-load rotate the engine and, one by one, check the gap between the top of the plunger and the bottom of the circlip - when the lifter is on the heel of the cam .

It should be about equal to the diameter of the wire that the circlip is made of. That is a sufficient pre-load and you'll never have to worry about bottoming out.