Prestolite Distributer rotor wobbly, what's correct part number or is shaft worn??

[Elizabeth_B29]

Hello Afourians,
I have an older used rotor that has a shorter profile than the Borg Warner that I received when I ordered a new rotor.. It sits snug on the distributer shaft and a bit farther down into the distributer. Still looks to be in line with the contacts on the inside of the distributer. The A4 runs great. I think the boss on the inside of the rotor is in deeper and making better contact than the new one I ordered, giving a more snug fit, possibly due to it being shorter.

Two of the new rotors I ordered are taller and will not push down as deep into the distributer, don't think the boss inside the rotor is getting enough bite on the groove in the dist shaft. They are loose on the shaft and wobbly....think this added to the pandoras's box of ignition issues and getting her initially running and was helping to give me a knock and a miss due to the wobble.

I tried sanding the bottom off one on a bench belt sander and hacked it up but think this may be a solution if the shorter one is no longer available. Maybe I will use a guide or fence next time...

This older one that fits doesn't look like it had its bottom sanded off.
The plastic is smooth and rounded.

Anyone know the part number of the lower profile one?

Is my distributer shaft out of spec?

Is sanding off the bottom a viable fix and possibly shiming the inside of the rotor.

or does any of this really matter???????? After finally realizing how robust these engines really are, I probably could just duct tape a large paper clip onto the shaft and it would run, well maybe with a little knock and a miss.

Cheers!

Elizabeth

EB_29

[ndutton]

From whom did you order these rotors, MMI or somewhere else?

One call to Ken in parts and . . . . . DONE!!

[Dave Neptune]

Elizabeth, I had the same problem with the "rotor's fit" on the shaft. I went through about 4 or 5 until I found one that fit. It was a production run that was bad and I got two of them twice in a row after finding the first replacement the same. However mine is a Delco and not the Prestolite. In my years of doing engines this scenario is not new to me.
Note it is for this reason I "fit" any extra "parts" for the boat before storing them. Don't want to be out there replacing a simple part only to find it does not fit!
Also there are spring kits for these distributors once converted to E/I. New spring won't hurt and they are lighter as there is no longer drag on the cam from the shoe on the points.

Dave Neptune

[joe_db]

BMW did something similar. I would take 10 air filters out to the car and give the dealer back the 8 that did not fit

[marthur]

Note it is for this reason I "fit" any extra "parts" for the boat before storing them.

I have had a rotor that did not fit well on my Delco distributor. That is why I also do this. What I usually do, though, is to install the new part and keep the working original as the spare.

I do have a working early model Prestolite distributor sitting on my spare engine. If you would like any measurements for comparison let me know.