The Dodge Challenger Message Board

Have problem with loss of valve adjustment with a 440 with a hydraulic roller cam and Edelbrock heads with roller rockers. After adjusting recomended preload the engine runs quite for a while and then starts ticking on valves. New adjustment, silent for a while and then ticking comes back. New adjustment, silent for a while and so on.. Have discussed this here earlier and got several tips (thicker oil, rensing of oil journals, checking push rod lengths, etc). Gone through it all whithout success. Taken everything apart whitout finding any damages (cam loobs perfect, straight push rods, no broken or bent rockers, lifters working properly, etc) no mechanical wearing on any parts, no metal in oil... Recently got a new tip saying that the aluminium close to the adjustment threads in the rockers can be gradually exhausted and result in a repetetive appaerence of valve lash. Anyone have experience in this or heard of it? / Lars

So tell me, every time you adjust the preload, does your adjuster have to go slightly more down every time?

If so you must be getting high wear somewhere. The only places I can think that wear will be is on the base of the lifters or the top of the cam lobes.

Were these new lifters and cam?

Had the lifters ever been used with another cam?

Was the cam broken in correctly on first fire-up?

It does sound to me as if the cam is wearing. I would look for a problem there.

Just another thought. Are the lifters a good fit in the bores? If there is wear in the lifter bores the lifters can 'cock' to one side and dig into the cam lobes.

So tell me, every time you adjust the preload, does your adjuster have to go slightly more down every time? / Yes

If so you must be getting high wear somewhere. The only places I can think that wear will be is on the base of the lifters or the top of the cam lobes. / That was one of the first thoughts, but no, there is no wear neither on the cam lobes nor on the lifters.

Were these new lifters and cam? / Yes

Had the lifters ever been used with another cam? / No

Was the cam broken in correctly on first fire-up? / Yes, and engine primed, showing good and consistent oil pressure.

It does sound to me as if the cam is wearing. I would look for a problem there. / Have looked. The cam is perfect.

Just another thought. Are the lifters a good fit in the bores? If there is wear in the lifter bores the lifters can 'cock' to one side and dig into the cam lobes. / The bores were not renovated/brushed during build up, but they look OK. Doesnt it have to be quite heavy wear to make lifters cock? And as you say shouldnt that show up on the cam lobes?

So again what do you think of the "material exhaust theory"? I talked to a guy who had thsi problem but hes the only one I have heard of having that problem. And I have talked to many...

Thanks for your comments, looking forward to more / Lars

Normally the lifter bores would have to be well out of spec to damage the cam lobe but, as was found out recently, cams with very high rates of lift are very prone to damage if the lifters are loose.

Roller cams tend to make the lifter bores oval in shape very fast so people changing from rollers to flat tappets can have problems too even though the side-to-side tolerance may be OK.

Lets face it. If you have to drop the adjuster further down every time then the distance between the cam and the top of the pushrod must be getting shorter. That MUST be the cam or lifter. I cannot see how it can be anything else. I do not understand this about exhausting metal from the rockers. That does not sound logical at all to me unless I have not understood. You would have to have all the threads moving up the rocker.

You are sure the adjusters are locked tight and do not move? Try marking them somehow to see if they have rotated the next time they go loose.

The only other way they would keep going loose would be if the valves were seating less and less or the stem length getting shorter. I don't see that as a possibility either.

I take it you are adjusting to zero lash and then adding a half turn or so of pre-load?

Normally the lifter bores would have to be well out of spec to damage the cam lobe but, as was found out recently, cams with very high rates of lift are very prone to damage if the lifters are loose.

/ Yes thats true. However the cam is failrly mild 218, 228 lift 544, 544 and again I think I would see some damage.

Roller cams tend to make the lifter bores oval in shape very fast so people changing from rollers to flat tappets can have problems too even though the side-to-side tolerance may be OK.

/ OK but this is going to roller.

Lets face it. If you have to drop the adjuster further down every time then the distance between the cam and the top of the pushrod must be getting shorter. That MUST be the cam or lifter.

/ Or rocker!

I cannot see how it can be anything else. I do not understand this about exhausting metal from the rockers. That does not sound logical at all to me unless I have not understood. You would have to have all the threads moving up the rocker.

/ Yes thats exactly what this guy told me. He said that turning the adjustment bolt will become harder and harder as the metal around the threads collapses and finally the whole thing will pop out with threads and all. I also have problems believing it but Im running out of explanations... Thats why Im asking if someone else have heard about it.

You are sure the adjusters are locked tight and do not move? Try marking them somehow to see if they have rotated the next time they go loose.

/ They are thight. Have checked several times.

The only other way they would keep going loose would be if the valves were seating less and less or the stem length getting shorter. I don't see that as a possibility either.

/ Neither do I. It would mean burnt valves and lots of power loss. It runs fine even when ticking.

I take it you are adjusting to zero lash and then adding a half turn or so of pre-load?

/ Yes 3/4 turn.

Thanks again and please keep an ear open if you or someone else hears about exhausted rocker threads. I have also sent the question to Hughes (bought almost all parts for build up there) but no answer so far.

/ Lars

What make rockers are they? Are these the ones Hughes sells that are blue or red ally with roller tip?

I use the same type of rocker (although not bought from Hughes) and use a bigger cam than that without any problems at all.

A couple of years ago there were some rocker makers (mostly Crane) that were using bad adjusters that were failing. Different problem to yours.

A friend of mine was using pushrods that were slightly too long. These were catching one edge on the underside of the rockers and causing the rockers (Crane) to flex which was eventually snapping the adjusters off the top of the rockers.

These are the only rocker problems I have heard of.

What make rockers are they? Are these the ones Hughes sells that are blue or red ally with roller tip?

/ 1.6 blue with roller tip.

A friend of mine was using pushrods that were slightly too long. These were catching one edge on the underside of the rockers and causing the rockers (Crane) to flex which was eventually snapping the adjusters off the top of the rockers.

/ There are no marks on the rockers were the pushrods would contact them if they were too long, so I dont think thats the problem either.

OK thanks again. I will try to crank the engine whitout intake and valey pan to see/listen if I can get some clue on whats going on. / Lars

Same rockers i am using then.

Be aware you will not get full lift on the valves unless you have full oil pressure and cranking will probably not give you that.

Had a thought during the night (when I am asleep is the only time my brain works).

I cannot remember what size the adjusters are but they must have about 24 threads per inch yeah? That means a full turn is 40thou?

So if you are using 3/4 of a turn to set preload you are pushing the pushrod down about 30thou every time.

How many times have you had to do this because you have lost all preload? Three?

Let me say three. So that would be 90thou lost during that time.

So this theory about the threads somehow creeping up inside the rocker says that the threads have all moved up by over two turns without stripping? That just is not possible.

PLUS!
If the pushrods are the correct length then when you first installed them and the rockers the adjusters would be set so that you have just one or two threads showing under the rocker after setting your pre-load. Any more or less and the pushrods are not the right length.

If you are having to add more pre-load every time because it has 'vanished' then your adjusters must be showing 4 or 5 threads under the rockers by now yes?

So is this the case at present? You now have more threads showing under the rocker and the pushrods are now too short?

Had a thought during the night (when I am asleep is the only time my brain works).

/ To me it seems to work quite well also during daytime. Mine only works when Im doing the dishes. Unfortunately/fortunately that doesnt happen to often.

I cannot remember what size the adjusters are but they must have about 24 threads per inch yeah? That means a full turn is 40thou?

So if you are using 3/4 of a turn to set preload you are pushing the pushrod down about 30thou every time.

How many times have you had to do this because you have lost all preload? Three?

Let me say three. So that would be 90thou lost during that time.

So this theory about the threads somehow creeping up inside the rocker says that the threads have all moved up by over two turns without stripping? That just is not possible.

/ Sorry, I left out a bit of information of the problem: The valves that loose adjustment are different at different occasions. It is normally one or maybe two valves that need adjustment every time it starts ticking. And although I havent kept a record which ones it is I see no system in it. Both sides for instance. Apparently random. Adjustments have been made maybe 5 times. Dont know if I have been on the same one several times.

PLUS!
If the pushrods are the correct length then when you first installed them and the rockers the adjusters would be set so that you have just one or two threads showing under the rocker after setting your pre-load. Any more or less and the pushrods are not the right length.

If you are having to add more pre-load every time because it has 'vanished' then your adjusters must be showing 4 or 5 threads under the rockers by now yes?

/ Have to count.

So is this the case at present? You now have more threads showing under the rocker and the pushrods are now too short?

/ Dont think so yet. But Im getting there...

Why dont you take an afternoon nap and let your brain work at 10.000 rpm again. Your analyses are big help. THANKS!!!

/ Lars

Are you 100% sure that when you are setting pre-load that each lifter is on the base of the cam lobe in turn?

Which method are you using to ensure you adjust the correct rocker for every 90 degree turn of the crank?

I have a feeling this has something to do with the way you're setting these up and not a fault as such.

Are you 100% sure that when you are setting pre-load that each lifter is on the base of the cam lobe in turn?

/ Yes, pretty sure.

Which method are you using to ensure you adjust the correct rocker for every 90 degree turn of the crank?

/ Just follow the timing order and adjusting when valves are fully closed at ignition.

I have a feeling this has something to do with the way your are setting these up and not a fault as such.

/ Dont think so. After adjustment its quite. If there would be something wrong with adjustment ticking would show upp immedeately.

But I was wrong about getting push rods to short. If the "material exhaust" theory is correct its only the internal distance; adjustment bolt vs. rocker thats changing. Vertical position of push rod top and rocker tip would be constant.

Actually I can only see two possible explanations. Either the material exhaust thing or some unidentified problem with oil pressure in the lifters. But what should that be?

I take your point about the rocker to pushrod distance. But I do not see how a thread can 'walk' up a hole and not strip.

Oil pressure in the lifters is not the problem because you set preload with zero pressure anyway.

However your method of adjustment is slightly flawed. In fact it could be the cause of your problem.
Adjusting both valves at TDC on each cylinder in turn is not recommended by any of the cam or rocker manufacturers. They all insist that for the lifter to be absolutely rock bottom on the cam lobe the other valve must be open.

I have copied this from the Crane Cams web site.

1. Remove the valve covers, and pick a cylinder you are going to set the preload on.

2. Hand rotate the engine in its normal direction of rotation and watch the exhaust valve on that particular cylinder. When the exhaust valve begins to open, stop and adjust that cylinder’s intake rocker arm. (Why? Because when the exhaust valve is just beginning to open, the intake lifter will be on the base circle of the lobe, the correct position for adjusting the intake.)

3. Back off the intake rocker arm adjuster and remove any tension from the pushrod. Wait a minute or two for that hydraulic lifter to return to a neutral position. The spring inside the lifter will move the pushrod seat up against the retaining lock if you give it time to do so. (If you are installing brand new lifters they will be in the neutral position when they come in the box.)

4. Now spin the intake pushrod with your fingers while tightening down the rocker arm. When you feel a slight resistance to the turning of the pushrod, you are at “Zero Lash”. Turn the adjusting nut down one half to one full turn from that point. Lock the adjuster into position. The intake is now adjusted properly.

5. Continue to hand turn the engine, watching that same intake. It will go to full open and then begin to close. When it is almost closed, stop and adjust the exhaust rocker arm on that particular cylinder. (Again, when we see the intake almost closed, we are sure that exhaust lifter is on the base circle of the lobe.) Loosen the exhaust rocker arm and follow the same procedure described before in steps 3 and 4 to adjust this rocker arm.

6. Both valves on this cylinder are now adjusted, and you can move on to your next cylinder and follow the same procedure again.


I have a chart that will allow you to do this more quickly by adjusting two valves on different cylinders at the same time for every 90 degrees of rotation. I cannot find it on here so I will post a scan of it from home tonight.

OK, thats something new to me. Id very much appreciate that chart. Ill do a new adjustment according to that after Sweden have won over Italy tonight.

Here's the chart from the Mopar Performance catalog

Thanks Steve!

Here is a better scan of that lash/preload setting chart.

As you can see the lash on #1 intake is set 90 degrees past TDC. I am sure this must be the source of your problems.

I usually mark the crank pulley where it just meets one side of the fan belt. Then make 3 other marks 90 degrees apart so I know exactly where I am when doing this.

Have set preloads according to the chart. I´ll be back with an evaluation report after some time of driving. Will first go through some other accumulated irritating defects while fingers are dirty. But not before the quarter finals. Looking forward to a Sweden - UK battle. Holding my thumbs for you tonight. Shouldn´t be any problem. After all you do have a Swedish coach. And thanks ahgain for all help. / Lars

Football? What's that? Never heard of it.

I'm with Tommy from now on. Stupid bloody game.

I have spoken with some Chevy-boys (lost souls ) about this. The method that they use is that they adjust the lifters when the engine is running!

They do it like this:
(First of all it is adviced to have an old valve cover that you can use to keep the oil in the engine. You simply chop off the top of the valve cover so that only the side walls are left.)

When the engine is idling, loose the bolt/nut until you can hear a ticking sound. Then tighten the bolt until the sound disappears. After that you tighten the bolt/nut 360 degrees and then you are finished.

This is a superior way of doing it according to them. I know nothing about this myself, but I thought I would post their recommendation. Maybe it is possible to use the same method on our Mopar engines?

It would work doing it that way.

BUT it WOULD be very messy and oil will splash all over the place.

I still think doing it the right way is best. I know EXACTLY how many thou I have compressed each lifter in my engine and for me that is something less to worry about.

Both of the Chevy-guys I am referring to have 20+ years of experiance each from street racing cars/drag racing cars. I trust them to 100%. They are far more experianced than myself (doesn´t say very much maybe ).

Yes, it can be a bit messy, but I think that this method is worth a try if everything else fails. It souldn´t be any risky business unless your ears are clogged with oil or something .