Valve Lash Adjustment

-
wazoo64

wazoo64

Well-Known Member
Joined
Aug 22, 2006
Messages
766
Reaction score
14
Location
York, South Carolina
How often should this be checked? I have a new build and have already had to fix a noisy rocker.
Is this something that requires constant attention on a 550HP roller cam engine?
 
Hydraulic roller or solid? If it's solid, then yes, they need to be checked often. For example, I worked with a guy who had a small block Chevy with a Comp Cam solid roller, approx .640" lift in a car that he drove daily. He checked the valve lash once a month. Solid rollers are unforgiving if you let the lash get too loose, even on a Mopar with it's superior shaft mounted rockers.
 
wazoo64,

There are many factors (ramps, lift, spring pressures, pofile...etc.) but it should not require constant attention. Sometimes a header leak can fake you out and sound like a lifter/rocker.

A couple of motors ago I found I was adjusting it all the time.. you can see by the picture what I found. Moral of the story is if you are adjusting them all the time you may have an issue brewing.

Kory

BadLobe2 5-22-04 (Small).JPG
 
It's hydraulic roller and new (1000miles) professional build by Joe Sherman. He said that in theory I shouldn't need to keep adjusting. It's just a little concerning to me as to why one lost it's position.
 
I am still looking for some info on valve lash adjustment. My lifters have become noisy and I want to go through all of them. Is there a best practice for performing this procedure? I have a full Hydraulic roller with 1000miles. For some reason they need some adjustment already. Any info would be great.
 
A hyd. lifter should require no adjustment after the proper preload is set. sometimes when you get a new motor it might require going through it once if they are a little noisy but nothing after that. set the preload to about .040 and that should be it. if you keep having to tighten one or a few more and more that is a sighn of a failure like a lobe going flat.
 
when you say lash I hope your not meaning a clearance between the rocker and valve tip like on a solid cam. hyd. require pressure where the pushrod is keeping the lifters plunger down.
 
camd64 said:
when you say lash I hope your not meaning a clearance between the rocker and valve tip like on a solid cam. hyd. require pressure where the pushrod is keeping the lifters plunger down.
Click to expand...

Maybe its not the right teminology but what has happened is some noisy lifters. One was really bad and we were able to tighten up the adjustment and the noise went away. I had this engine built professionaly by Joe Sherman and lately it has been getting noisy up top and idle is rough. I have the valve covers off and would like instruction on how to check the lash. This is a bit over my head but I was told the adjustment can be done fairly easily in the garage. Any direction would be appreciated?
 
I do it the slow way but its always worked for me. first after you have the cover off look at the first rocker and either using the starter to bump the motor or turn the crank pulley by hand watch for the rocker to come all the way up, telling you the valve is all the way closed and the lifter is on the back side of the cam lobe. once that is done loosen the set screw on the rocker and back it off all the way so the rocker is loose. now you need to take adjuster on the rocker and turn it until you feel it stop against the pushrod and don't tighten it, stop as soon as you feel tension. at this point you have "zero lash". that basically means the pushrod has no more play up and down. the last step is to then turn the adjuster down another half to a full turn. most adjusters are 24 threads per inch so one turn equals .040. lock that adjustment down and move on down the line.
 
Check and see after you do this if any of the adjusters are further down than the others indicating a problem like a wiped lobe or bent pushrod, etc.
 
Did your engine builder dyno your engine? Who broke-in the motor and was it down properly? Was the oil pressure brought up by prelubing (spinning up)the oil pump before the engine was started? Your hydraulic roller cam should be pretty maintenance free if all was done right by the engine builder ( on a high revving motor like yours 1/4 turn is enough preload for a good lifter) and the parts were matched correctly ( right springs, rocker arms, pushrods, lifters, etc.) Make sure you've got your rocker arm lock nuts locked down correctly.
 
camd64 said:
I do it the slow way but its always worked for me. first after you have the cover off look at the first rocker and either using the starter to bump the motor or turn the crank pulley by hand watch for the rocker to come all the way up, telling you the valve is all the way closed and the lifter is on the back side of the cam lobe. once that is done loosen the set screw on the rocker and back it off all the way so the rocker is loose. now you need to take adjuster on the rocker and turn it until you feel it stop against the pushrod and don't tighten it, stop as soon as you feel tension. at this point you have "zero lash". that basically means the pushrod has no more play up and down. the last step is to then turn the adjuster down another half to a full turn. most adjusters are 24 threads per inch so one turn equals .040. lock that adjustment down and move on down the line.
Click to expand...

Great summary and easy to understand. This is the way I will proceed unless anyone here disagrees.
 
There should be absolutely no need to adjust the rocker arms if they were properly adjusted the first time. And as Johnny said hydraulic cams don't require any lash. Lash is clearance needed by solid cams. Hydraulic cams whether flat tappet or roller style require preloading the lifter. If things are wearing and your getting lash in the valvetrain that isn't good at all and should be thoroughly inspected immediately because something isn't right. If you run it you run the risk of causing a major problem. If I were you I think I'd call the engine builder and tell him what's happening.
 
I spoke with the engine builder and he said it would be a one in a million to have a roller cam go bad in the first 1500miles. He suggests a push rod issue if there is any at all. I am going to adjust these with 0 lash plus 1/2 turn of preload and see what kind of result I get. I will inspect the pushrods for any obvious wear or bends. If anyone has a tip for inspecting the pushrods while in the engine let me know. I would prefer not to pull the rocker assemlby off unless absolutley necessary.
 
wazoo64 said:
I spoke with the engine builder and he said it would be a one in a million to have a roller cam go bad in the first 1500miles. He suggests a push rod issue if there is any at all. I am going to adjust these with 0 lash plus 1/2 turn of preload and see what kind of result I get. I will inspect the pushrods for any obvious wear or bends. If anyone has a tip for inspecting the pushrods while in the engine let me know. I would prefer not to pull the rocker assemlby off unless absolutley necessary.
Click to expand...

Hate to rain on your parade, but I've seen a roller cam go bad in less than 1000 miles.

You should be able to spin the pushrods if you back off the adjusters a bit, then tighten them until they are just at zero lash. You should be able to see if they are bent by spinning them. If one or more are really badly bent, you'll be able to see it easily and won't need to spin them.

The best method however is to remove the rocker assembly and roll the pushrods one by one on a piece of glass.
 
lilcuda said:
Hate to rain on your parade, but I've seen a roller cam go bad in less than 1000 miles.

You should be able to spin the pushrods if you back off the adjusters a bit, then tighten them until they are just at zero lash. You should be able to see if they are bent by spinning them. If one or more are really badly bent, you'll be able to see it easily and won't need to spin them.

The best method however is to remove the rocker assembly and roll the pushrods one by one on a piece of glass.
Click to expand...

Thanks good info....accept for the part about the cam...if that cam is damaged I will not be happy.
 
Wazoo I have to agree it is pretty odd for a roller cam to go bad but as lilcuda noted anything is possible but I wish you the best of luck. Also I'd like to say that I know you don't want to pull the rocker shafts off but that's probably the only way you'll get the pushrods out to inspect them and you really should do it. In about 30-40 minutes you should be able to pull the rocker shafts off, take each pushrod out to inspect them and have a look down inside to see if everything looks ok and there are no metal shavings floating around due to something being worn so it's well worth your time.
 
You would hope there are no metal shavings after a new build like this. My gut says its a bent push rod or just some minor adjustment needed. If I do replace the pushrods what should I use? Also I have access to small flexible scopes to explore the inside without a teardown. Has anyone ever done this? Curious if I can get to the cam with a small scope. I would like to rule out any damage to the cam as well.
 
With the increased pushrod angle caused by taller roller lifters, check to make sure the pushrods aren't rubbing the heads in the pushrod holes. I had to open up my holes in the heads to prevent this.
 
When you pull the valve cover, take a look through the heads. It's a strait shot down to the cam and lifters.
 
wazoo64 said:
You would hope there are no metal shavings after a new build like this. My gut says its a bent push rod or just some minor adjustment needed. If I do replace the pushrods what should I use? Also I have access to small flexible scopes to explore the inside without a teardown. Has anyone ever done this? Curious if I can get to the cam with a small scope. I would like to rule out any damage to the cam as well.
Click to expand...

There shouldn't be an metal shaving unless there is a problem where either the cam, lifters, and/or pushrods have a problem. I mentioned it because you have a valve train problem of some sort so you need to make sure there isn't any trash floating around in there that will eat the bearings. On a flat tappet cam it's easy to pull the lifters out using a heavy duty magnetic pick up tool then you can inspect the lifter and cam lobe. The problem is you have roller lifters that are tied together with a bar which will most likely make that impossible. Talk to your engine builder as to what pushrods to use. He knows what the rest of the setup is so he should be able to recommend what's best. He should also know what length pushrods he used which is something you'll need to know when you order them. You can try inspecting with the flexible scope. Don't know how much luck you'll have but it can't hurt. BTW: if you have an extra one of them feel free to float it my way. LOL

 [/quote]
70dart340 said:
With the increased pushrod angle caused by taller roller lifters, check to make sure the pushrods aren't rubbing the heads in the pushrod holes. I had to open up my holes in the heads to prevent this.
Click to expand...

I've heard of a few other guys having to do this when using roller cams. If one of the pushrods did contact the head it's possible one is bent.
 
So I tried to do a full adjustment today and got some terrible results. The engine fires up but terrible idle and backfires. Something went wrong. We adjusted each rocker with same tention but I think we may have went too tight.
We tightened until the pushrod would not spin easily in our fingertips and then added 1/2 turn more. Do you think we went too tight? I was thinking I should back them all out 1/4 turn and see if it runs better loose.
My builder said its one in a million to have a bad roller cam or pushrod at this point. If there is a problem it would be with the hydraulic lifter. Those seem to have failures more frequently.
 
did you rotate the motor/cam to the heel/bottom on cam lobe, for each valve ?? before you adjusted the rockers ?? you have to rotate the motor ,,and cam to adjust each rocker,, what type or rockers and push rods do you have ?
if you have bent push rods there is a resone for that,either incorrect push rod length or very high spring tension,and not a compatable push rod,,
you may need to pull a few lifters and inspect the cam and lifters,

can you se if your getting oil to the rockers ?
 
You must log in or register to reply here.
-

Back
Top