One day I could hear, what sounded like, the rotor hitting the posts as it rotated. Put my hand on it. Sure feels like it is. He replaced the cap and rotor because the post contacts were looking arced real bad.

New rotor was scrubbing the inside of the top of the new cap. Thought that the rotor was pressed all the way down. Trimmed the top of the rotor to be sure it was not scrubbing the cap.

Still felt like the rotor was hitting the posts.

The distributor was the original out of the 305 (that the 350 replaced) so about 14 years old. Got a reman off of Ebay.
Same sound and feel.

Got an ACdelco cap and rotor. Same sound like the rotor was hitting the cap posts. It was not. Was adjusting the timing and noticed that if I tighten the hold down clamp some more, the noise got real bad.

Pulled off the hold down clamp. The distributor has some wiggle room where it goes through the intake manifold. It also appears to not set fully down, as in the shoulder does not rest on the manifold. Maybe a gasket or 2 or 3 gap.


Pulled the dist.
The wear pattern is on the very very bottom of the teeth.

I looked at the old one that came out. It's wear pattern is in the lower 20-40% of the gear. I did notice that the cross-pin that engages the oil pump shaft is more chisel shaped. The reman unit is more blunt. I'm guessing that it did not fit all the way into the pump shaft, thus the dist not setting all the way down.

I was going to swap back in the old dist, but it does not rotate very smooth as compared to the reman unit.
Any ideas ???

Distributor is the external coil type.

 

That's a weird one. You sure the oil pump intermediate shaft is all the way down on the oil pump input shaft? Stock ones use a plastic collar that clips on both the intermediate shaft and the oil pump input shaft. Often (on a new motor) it's possible you simply didn't get that plastic collar "clicked" down into place on both shafts- which makes it ride high. I can't imagine it would prevent the distributor from dropping all the way home under the force of the hold down clamp, though.

Might want to yank the distributor shaft from the new distributor and then manually see if it fits the slot on the end of the oil pump intermediate shaft (as you lay across the motor with a flashlight).

Beyond that..... were the block, heads and/or intake milled heavily during a recent rebuild?

 

Sounds pretty straightforward to me....

Your dist gear needs to be shimmed; or, your housing or gear is WORN COMPLETELY OUT. I think, if you take the dist out and look at the end play, you'll probably find that it has in excess of .125". Should have something more like .020" (although few stock ones are that tight).

Drive out the roll pin, make a note of which way the gear goes on the shaft (dot aligned to rotor, or dot opposite rotor; I forget which it is). Get a new roll pin if necessary. They're at any REAL parts store, even a NAPA. If it still has too much end play, you could try adding shims to it, to take some of it out; or you might want to look at it real close, and see if there's something wrong, like the top of the gear ate up. The gear out of the other dist might be better.

In other words, make one good one out of your 2 bad ones.

 

Really stupid question, but did you make sure the slot on the dist. shaft keyed in with the pump? It wont just drop in. That will cause the dist to sit high. This would also make a hell of a racket as the slot skipped over the end of the intermidiate shaft. Id be surpised if the oil pump worked at all in this situation, though, so this is unlikely.

 

Oil pressure was 50 pounds and still had the noise.
Dam...did not know about the dot on the gear and rotor alignment. Which way is it?

The gap with the dist in was 2-3 gaskets worth.

Am I able to pull out the pump drive shaft for inspection? Can I get it back in AFTER inspection?

No know milling of heads/intake/block.

The old dist set in good, when clamped, nice impression in the gasket. Old dist gear looks good, no wear indication at the pump shaft end contact.

I was planning to put the old gear onto the reman. Then I decided to get a better look at the pump shaft. I can look at it but I have trouble seeing what I am looking at.

 

Sorry.... it doesn't really matter all that much. If it's backwards, all that will happen is, since the dist gear has an odd number of teeth, it will offset the shaft and therefore the dist body, slightly off of straight once the ignition timing is properly set. It'll just look goofy and maybe not fit to a real tight air cleaner, is all.

No you can't remove the oil pump shaft.

There's no way the oil pump shaft can cause this. If it was too tall somehow, and the dist housing was bolted tight to the intake like it belongs, all that will happen, is the dist shaft and OP shaft will be bound up something fierce. But the dist shaft can't move upward in the housing, beyond what the shims allow it to do.

2-3 gaskets sounds like kind of alot. Those gaskets are about 1/16" thick. That's like WAY WAY WAY too much end play; about a factor of 10 too much. THat's probably your problem. Reinforced by the wear being on the VERY BOTTOM of the teeth; the shaft is being forced upward as high as it will go by the friction of the gear teeth (which is the direction the cam gear is trying to make it go....), thereby only letting the bottom of it touch the cam gear.

You need to shim the end-play out of your dist, or get another one.

Remans are never any better than any other worn-out stock units about that. In fact, a typical reason somebody buys a reman, is just that. Then, they turn in their core; the "reman" place gets it, takes it apart, cleans it up, replaces the electronics, whatever, but they NEVER dink with the shims; it goes back out the door in a box as a "reman" with the same play it came in with. That's probably what you've got.

 

It seems the reman distributor may have been shimmed the wrong way, or it may be the result of a used distributor shaft being installed in a different, incompatible housing (poorly done repairs). The only way to be certain is to measure and compare the lengths from the lower end of the shaft to the mounting shoulder.

Another means to check this quickly is to compare the position of the reluctor moving pole piece to the stationary piece. If the moving piece is not approximately vertically centered in the stationary pole piece, the distributor may have been assembled incorrectly.

A distributor can wear at both ends. Since the cam gear engagement pattern tends to push the distributor shaft upward, it would stand to reason that more axial wear would occur at the lower bearing, and more radial wear would occur at the lower bearing. However, this isn't always the case, and a reman facility may be making improper assumptions. If a worn distributor had 0.100" of axial play, and all the shim were installed at the upper end with no regard to finished length, the shaft could ride very high. That could create a condition where the oil pump drive shaft is barely engaged (possibly causing that chisel-like wear you are seeing), and also cause rotor interference. Too low, and the reluctor may wipe out the pickup coil, or the distributor may not seat fully in the intake opening.

An incorrect shaft in an incompatible housing may cause both such conditions, and possibly more.

If your old distributor has only axial play, and the radial play is minimal, you can shim it and reinstall it. While the final lash may be a point of contention, it seems that most people whom I would trust are satisfied with 0.015-0.020" as a minimum clearance/axial play limit. Some like a little less for tighter control, and some like a little more to assure adequate lubrication of both bearings. That range seems to satisfy most schools of thought.



I can speell, reelie I con...

 

You guys are awesome. I'll look into this stuff.

. . . when the monsoon quits.

 

Ok, had a problem like this. The distributor wanted to stick up out of the intake about 1/16 in. Went to a wrecking yard got another and it fit fine. Ive had to shim a distributor, using three dist gaskets to do so. Maybe its not right, but it worked

 

OK...finally got pictures & more info.

These are pics of the old 305 pump shaft.
305_1
305_2

These are pics of the problem 350 pump shaft.
350_1
305_2

These are pics of shaft.
shaft_1
shaft_2
shaft_3
shaft_4

I measured the distance from the intake hole to the top of the pump shaft and compared the 305 & 350. Same.

I measured the depth of the slot on the 305 & 350. Same.

I inserted the old shaft into the 305 pump shaft. Fits good and drops in good. Inserted into the 350. Doesn't drop into the slot very far.

I inserted the new shaft into the 305 pump shaft. Fits good and drops in good. Inserted into the 350. Doesn't drop into the slot very far. Even less than the old shaft.

My conclusion...the pump shaft slot is not wide enough to accept the dist shaft, thus why it rides high. the "point" of the new dist shaft is even more blunt than the old dist shaft so it barely would engage the slot.

My fix...remove material from dist shaft so that it fits into the pump shaft completely.

Your thoughts ????

 

Kicking this back up....

 

Get a new pump shaft. One with a steel sleeve, especially if you don't have one already.

I can't imagine hassling over a $10 part. Take your distributor to the parts store if you want, make sure the new shaft fits properly into the distributor shaft.