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So I tore off my intake manifold to see what I could see. I found a lifter, near the tapping sound, that has a tweaked pin. I mean the retaining U-shaped pin that holds the insides inside of the outside. One of the legs of the pin is bent inward and is not retaining.

My valve stems are slightly misaligned. The second to most rearward valve stem sits a slight bit high, but the last one sits pretty far low. But the same goes for the other side, and I'm not having any trouble out of that side (yet; jinx). With a straight-edge on the valve stems, I can get a .019 feeler gauge in between the last valve stem and the straight-edge.

I stripped off my rocker shaft. There are grooves in the shaft that can catch my fingernails. It is also bent. It is bent such that when I lay it against the straight edge, one end stands about 3/32" away from the straight edge.

So I will definately replace 2 of my lifters. I cannot see how that one with the maligned retaining pin could create the tapping, it's pretty loud. I will buy a new set of rods, and probably a rocker shaft. My rockers are pretty pitted and crappy, but before I buy half the parts I need, I'll be broke!

Oh also, I put Marvel Mystery oil in my gas tank, and the tapping damn near went away for a day. Any ideas on how it might have affected internal parts to do this?

Since crate engines are lookin pretty expensive, I need to fix mine first. & GD it I still can't post from my own machine :mad:

The cam looks (through the drain holes) like the lobes are intact, and doing fine. I'll keep posting until she's 100% again. Thanks all, Erik.
 

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Make sure you check the oil pressure. If the oil pressure gets low there's not enough to supply for all moving parts. Lifter tick is one of the symtoms. A new set of lifters is pretty cheap. You can do that on a used cam. I would do them all vice hunting and pecking only a couple. Also make sure to check push rods for straightness.

Good luck
 

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Bear with me as I only remember bits of your original complaints...

If you can catch your fingernail on the rocker wear areas on the rocker shaft, .003" or more isn't out of line wear-wise. Usually, with this kind of shaft wear, the rocker bore bushings are worn as well. This could cause noise during operation.

Can't remember...are the rockers the 1.76 adjustables? Nope, they're not *G* (checked old post)...that likely is part of the problem, considering how this engine has been rebuilt.

Valve heights would only be critical with non-adjustables and .019" isn't that big a deal, tolerance-wise...unless things were right on the edge, as may be the case here *G*

From what I remember of your original post, with the bent pushrods and rocker arm shaft, I wouldn't be surprised if you had problems with that side of the engine. Better to bite the bullet, save up the money and repair it right.

Now that the intake is off, you can pop the suspect lifters out and examine the cam lobes carefully. Compare with a known-good lobe. Wear often shows up on the acceleration ramp. See this picture

Get back to us with more details...

For other readers, the original posts on this problem are here and here
 
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