Stripped distributor gears, is a poor machine job to blame?

[zero cool]

So a few days ago, I was working on my Cherokee and the distributor shredded it's gears. When I pulled it, it had a decent coat of oil on the gears so I'm pretty sure it's getting enough flow through the timing cover.

The distributor is a modified GM HEI distributor. I did a little bit of measuring to make sure everything lined up correctly. I have 3 distributors to compare with each other and the modified HEI is a little off from the other two.

I measured each one from the face of the shoulder that the distributor rests on (the face that contacts the timing cover) to the very top of the distributor gear with my dial calipers.

First, I measured the original Prestolite distributor that came out of the 401.

That distance was 2.920"

Next was the MSD pro-billet distributor.

That measured out to 2.945"

Finally, the modified HEI.

That was 2.860". Not only that but it had 0.050" play and would close up to 2.810". The 30 year old Prestolite had basically no play and the MSD had just a barely perceptable amount of movement. Maybe 0.005" at most.

Putting it into the timing cover and looking at it, you can tell the modified HEI rides up a bit higher and doesn't reach as far down onto the oil pump shaft.

Is it possible that this shorter distributor is the cause of the shredding gears? Or is it within spec?

I've already bought replacement gears but if the distributor is out of spec and causing this failure, it would be a waste to just put new gears on.

What do the distributor experts have to say about my "custom" distributor?

[jeepsr4ever]

We have fixed about a bakers dozen HEIs that came from various sellers of jeep parts. They have ranged in error from the pin hole being in the wrong spot to the length of the spud being to long. I wont name any names but if you call in you can ask.