I've adjusted my rockers a couple times with no problems but couldn't even fathom doing with the engine running and rockers pivoting back and forth - call that man superman!

Brent,

In the Words of an infamous--------, I feel your pain!!!
You have recieved a lot of good responses to your thread. Two things that bear intense scrutiny:
1. The cup adjusters as mentioned earlier!! If you can prime the engine; Take out the distributor and run a drill motor on the oil pump drive, and check to see how much oil is coming off the cup!!!
I didn't see how much oil pressure you are running in this motor, but I like to see about 80 to 90 lbs and then I restrict the oil to the rockers depending on the requirement of the perticular engine. They all are a little different!! You should see a small oil line coming off the adjuster cup if everything is correct. The rocker design incorporates an oil galley through the rocker down the adjuster to the cup. Make sure this is functioning correctly!!
2. Cam bearings can diffenetly be the problem too. I can't tell you how many motors that I have torn down when they come in for a build, that have the cam bearing installed improperly. Also, there are two grades of cam bearings available. Fed Mog has come out with a race cam bearing that is harder that the stock replacement so that you can run more spring pressure. I use the Durabond hardened bearings in my motors. As previously mentioned, the oil galley runs underneath the cam bearings, so you are getting less support under the bearing than in other motors!!
If you give me a call, I can run you through some tests to try to check to see if its cam bearings, or the cup adjusters.
Thanks, Tom Lucas FE Specialites
916-339-0427
P.S. D Cooney brought my attention to your ongoing problem.

WHAT'S UP???
 

Brent Mills OK it's been a week . There are we at??? Did you take the week off? Come on , it's time to fit the car. This thread is getting long. It's a mistery that is time to solve. I'm WAITING:rolleyes: Hope you find the problem Brent. I will have a talk with GOD.:D Rick Lake

Brent,
One of my customers told me of your plight on the forum here and suggested I pop in. I am sorry to hear of all your troubles. I am 90% sure I know what is happening to your adjustment, although the answer may not be well received.

First, the push rod cups are wearing away due to lack of lubrication. The oil feed hole from the rocker is not enough for this design, it requires small block/460 lifters with oil feed holes and push rods with the corresponding oil feed holes to supply proper oil to these rockers. As the cups wear, the lash opens, -you have already seen this, but have been hesitant to admit it to yourself.

Also, check the roller tips on the rockers. Roll them around with your finger and see if they roll true and do not have any out-of-round or up and down type movement. There is a good chance they will have this movement.

Next, pull a rocker assembly apart and "feel" one rocker on the shaft. Try and move it up and down and then forward and back. Does it feel like there is a bit more clearance in the verticle direction? Not scientific I know, but I doubt you have a small bore guage to check bore id.

What I am leading up to are the typical failure areas we have seen with the POP rockers. They offer both ball and cup and ball and ball rockers, both styles have failed-wearing quickly away at the push rod contact point. The bronze bushings wear at the bottom of the rocker where the rocker arm presses up against the shaft-ie. they wear out of round. Lastly, the roller tip quickly wears into an oval shape on the inside, allowing the roller to act like an eccentric, tight against the valve tip one time and loose the next. (This really shows up when setting lash, as the now eccentric tip "grabs" the feeler guage as you try to remove it.) We have experienced this type of wear in less than 20 pulls on the dyno, so that would correspond with your short driving trips.

Now, it is IMPORTANT TO NOTE: we experienced these and other problems with the Precision Oil Pumps Rockers during the summer of 2002. We have not tried any additional POP rocker components since last year, prefering to stay with tried & true designs we are more familiar with. -----SO THIS INFORMATION IS A YEAR OLD.------Doug may have implimented changes in design and manufacturing since that time. But, I continue to hear stories like yours.

PLEASE, FOR THOSE READING THIS, IF YOU HAVE POP ROCKERS, DO NOT ASSUME YOU HAVE A PROBLEM. CHECK AND MONITOR THE ROCKERS PERFORMANCE. DO NOT CALL POP AND TELL THEM SUCH & SUCH SAID THIS OR THAT. If they have improved the product, it would not be fair to call Doug without due cause.

Good luck with your engine, we can all empathise with you in your frustrations.
Rob

Rob....a very well stated set of facts....talked with Brent on Tuesday and he described this adjuster ball...and these"POP" rockers...we would have expected oiling through the push rod and a small block lifter too...like you mentioned but that's not what they provided him....
only one of the rocker arm ball wasn't worn out...not enough oil for sure....I agree with the tried and true....
Your post was appreciated and your knowledge of these "POP" rocker problems is apprecaited.....and as you mentioned perhaps this was an old problem solved and Brent was provided with some old parts....
Thanks for the post on this topic...
George

Last year when my project started when I was reinstalling my intake manifold. My valve adjustments kept changing .I found two flat cam lobes and mushroomed lifters but the real problem was the center two rocker studs on both heads were pulling ,Heli-coils and all.Heck I had the alluminum heads all done at shop. and after reassembly 'I' found the studs pulled some more,enough to notice now. Had to go to an insert. I had to remove the heads again to havethe shop machine acurately .Head gaskets $32 each plus shipping.The pulling was not noticed by myself or the machine shop before.Heck! George sold me the inserts. The oilfilter had caught everything no damage to crank or bearings.

Rob, you hit the nail on the head my friend.
 

Geesh! I can't make anymore engine decisions by myself as they end up as more icing on the big crap cake.

Ok, what should I go with?

I have heard good things about the Erson setup (did with the Precision Oil Pumps rockers too). I know the name dove, but I have heard that they are not rebuildable, etc....

Erson? Dove? Something else???

Private message
 

Rob McQuarie Rob you have a private message and a couple of questions Thanks Rick Lake

Brent

I am sorry to hear of all the trouble you are having. Your problem may be that you have had two bad sets (poorly designed) of roller rockers. However, others seem to have used the POP and Harlan rockers with no problems. Also it seems like quite a coincidence that both failed for you. This might seem like a stupid suggestion, but I almost made this mistake while assembling my rockers ( the shelby stainless type) even though I was aware of the facts that two of the bolts that hold down the rockers are thinner (smaller diameter) than the rest. These bolts go into the holes that have the oil passages in them. This allows oil to come up around the bolt into the rocker shaft to oil the rockers.
Only a suggestion, seems like you checked everything else to no avail.

Paul

Brent,
Are you using bolts or studs to hold down the rockers? If bolts , it's possible that you are bottoming out before fully torquing down -thus the stands lift throughout the valve train causing haywire adjustments on lash. Its best to run bolts down and measure free length against the rocker stand height. If you are using studs, lifting rocker stands should not be a problem. Never use bolts in the aluminum heads because you will be asking for trouble.
Paul

Brent,
Pauls question is a good one and a timely one. Let us know what you find out if you used the correct bolts or type of studs on those particular stands?

It also made me wonder if your rocker shafts might have been installed upside down or something too?. Just a thought...

When Tom blueprinted my last seat of heads, he even provided some additional grooving to those particular studs to get even more oil flow into the rocker assembly.

What about the shafts that POP sells , Is the oil design ok, they look great !
Because everything is compatable with the original equipment , I have aftermarket steel stands ,
and just need to get "end supports" , I am thinking of using the shafts , end supports with original rockers .
What do you think .

any update on what the cause was ?

Wearing camshaft ?

As far as I can tell, it was soft adjuster cups. POP sent me new adjusters and I installed them (seemed odd that so many people don't have problems, but I did). I checked for good oiling at the cup of all of them (pre oiled with drill). About 100 miles later and it's still running well. :)

Great to hear of your good fortune! If the chance was 1 in 1000 wouldn't you know it had to be you:CRY: . Enjoy your car Brent - you deserve it!

Now this was a hard one. Lots of involvment by fellow cobra enthusiasts.
Good for you Brent, a cheap and easy fix. But recall how much time you spent on this , how much frustation and at the edge of giving up, only because someone has not done his job right and sold you crap. Someone, and that was one of my tips, forgot to harden the adjuster cups and shipped them out without checking their quality and left it up to you to figure out if anything is wrong.
I told you, cobra owners are masochists. They like buying high tech parts for their cars and engines and put up with having to be the quality control people, and even paying for it.
I am a masochist too, so never mind.
Enjoy you Cobra.

Brent Mills Gald to hear that the car is running. This kind of problems can drive anyone NUTS. I hope that whoever's adjusters made good on them. You should play the lottery with your luck. Happy Trails and it is good to see your SMILE:D Rick Lake

I live near Doug at precision (few hours away) let me know how this works out.