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Well, all I really could do was to press on the rockers to isolate the tapper. I'm pretty sure it's coming from the 4th pushrod from the rear of the engine, drivers side. I put in the long (9.62"), but the tapping continues.

I didnt find any loose rockers. I tried to push on the rod end of the rocker, but didnt get any clearance between the valve stem and rocker. I didn't find any play between the rockers and the rocker-shaft.

Could it be a bad lifter? A bad cam? Either way I guess I should order a new set of pushrods from summit. I don't think thats going to affect the tapping. Should I order fancy rods, in case I have to get a new cam (meaning a beefier hipo cam >:) ) and have to upgrade all my train?

Many of the faces on my rockers are a little pitted. The culprit rod's rocker has a peculiarly irregular footprint. It doesn't seem as though that small a problem could be the source of the tapping, especially since the longer rod isn't taking up slack.

I'm sure none of the parts that comprise this engine are of any type of quality, If the problem stems from one part, then good, I'll replace it. If that requires beefing up other parts, then good, I'll try to increase horsepower with better parts.

Anyways, I'm stuck again. And I'm finding this to be a much bigger problem than I hoped it was. Thanks again, for all the help, Erik.

PS the last post should be around 10 pages back.
 

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Have you checked the rockers and their shafts for play and wear? Your statement about the irregular tip wear pattern brought that to mind...I know you said you checked the rockers and shaft, but did you actually pull the unit and inspect them carefully (I'd likely pull a couple off and measure them but that requires precision instruments which I doubt you have)..

I'd like to hear Hal's opinion about leaving the suspect pushrods out and running the engine with that cylinder dead. I'm loathe to do that because of the possibility of a lifter popping out but I have had rocker studs fail in the past and have limped home with a pushrod bobbing up and down with no detrimental effects.

Maybe someone else can steer us in a different, more fruitful direction...

For others viewing, the orginal thread is here
 
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Hi, I'm sort of jumping in on this conversation... But
are you sure it's not a loose rod bearing? I know that
it can sound similar to a top end noise. One thing to
notice about top end noise -- is it's at half the speed
of lower end problems. Also, if you suspect a rocker
is bad have you turned the motor thru two revolutions?

Adam
 

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Just in case, which would you recommend if for some reason one would need to take of the rocker(s) from a cylinder. Run with or without pushrod in place. Wouldn't pushrod bounce into valve cover if left without rocker?
 

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Wouldn't pushrod bounce into valve cover if left without rocker?

You know, my first instinct, if I hadn't actually had it happen to me, would be to think that...

The story I shared was from back in my street racing days and, at that time, I drove nearly 15 miles home in the middle of the night (albeit at reduced speed) running on 7 cylinders. Didn't know until getting home and pulling the valve cover that a rocker stud had broken. The rocker was just laying there in the head, along with the stud, and the pushrod was still sitting there in its hole. I unscrewed the hex which was still there and installed a new stud and the old rocker, which appeared undamaged, set the lash (solid lifter cam) and was back in business. Drove the car for another 3 years before selling it...no problems, although I did break a couple more studs (this was before ARP stuff and before I could afford roller rockers for the street...all the good parts went into the race car *G*)

My instincts would prevent me from recommending such an action for diagnosis but figured I'd mention it so maybe someone else could offer up their experience or ideas. I just prefer to completely diagnose problems first rather than throwing parts and money at them in the hope of hitting the target..*G*

Given what I know now, if I was to do the deed, I'd do it without the pushrod...less stuff to go wrong *G*
 

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Heck i'd say it is a good time to get that comp cams pakage of cam, lifters, springs, locks, retainers and timing kit......

get a set of harland sharp roller rockers and screw in stud the
rocker studs.....

Have you checked you exhaust manifolds for an exhaust leak?
They can sound quite similar....A mechanic quoted my friend 1500
to fix the bad lifters and oil pump....I found that the exhaust manifold has warped a bit thus blowing the gasket.....we fixed it...

and it only ran him $65.....

so....make sure you leabe no stone unturned....

If it is time for a rebuild.....don't wait.....if a rod fails....it will be more costly in the end.
 

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Hey Erik, you might not see this cause I missed this post when you made it but here are my thoughts.

If you think you have the rocker arm identified but the tapping doesn't go away even with the longer pushrod then try this. Take a feeler guage and slide out a .020 blade. With the valve cover off and the engine fired up slide it between the rocker and the valve and see if the tapping stops or the noise changes. If it is in the valetrain and you are on the right rocker it will at least change the sound.

I would say if running the feeler guage under the valves on that side doesn't change the sound one of 2 things is happening. Either the problem is just not in the valvetrain, or a cam lobe has shaved and/or a lifter has had a catastrofic failure.

If #1; then there have been some very good sugestions - for sure make sure you are not mistaking an exhaust leak for a tapping sound. I've seen this one fool very good mechanics. If it is a rod bearing or even more likely a wrist pin you can usualy detect this by pulling the spark plug wire off of that spark plug, the noise will go away or become barely perceptible because the top of the piston is not getting hammered by the combustion every other stroke.

If it is in the valvetrain then - Listen to Mark, he's giving you the straight and skinny. Beg or borrow or rent a dial indicator with a magnetic base and check the lift. If you have a flat cam you will find it immediately without guesswork.
 
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