Distributor fun. Not sure why, but seems that every bought part these days has something off with it.
When I pulled the engine, I tossed the original distributor (and kicking myself) - and bought a re-manufactured Cardone unit from Summit. This was a mistake, as *eventually* I realized the bearings on the reluctor plate were notchy and causing the vacuum advance to work incorrectly, get hung up. This was a source of drivability issues.
The machinist that I took my failed engine main bearings too said they looked like they were a result of detonation. If the vacuum advance was hung up, then possibly he's correct - I'll try not to think about that too much.
Anyway, I bought a new Duralast distributor from Autozone, tossed the other distributor. Drivability improved.
Timing seemed a slow, so I decided to 'recurve' the distributor. Then timing seemed off the charts at 48 degrees total advance. Opening the distributor revealed 18L and 21L slots (measured with calipers, and by advance reading showing 36 degrees mechanical advance).
Thinking I could swap reluctor arms to a smaller slot one. I bought a remanufactured Motorcraft distributor for a 460 engine, and got 13L, 18L slots. Unfortunately the Motorcraft reluctor arms won't fit on the 'new' distributor shafts, the new distributor shafts are bigger diameter than the Motorcraft ones. In addition, the 460 distributor shaft is too short to fit into a 302, so I couldn't use the unit.
I accidentally bought a new Cardone distributor for our engines, and it came with 10L, 13L slots (approximate). The Duralast and Cardone distributors are different. They appear to use the same core, but machining and shafts are different. Reluctor arms do not swap between the two (so close, the height of the shaft is slightly different). The Duralast electronics are (seemingly) better quality, but it comes with 18L,21L advance slots.
I bought another remanufactured Motorcraft 302 distributor, and it came with 16L, 21L arms.
All remanufactured Motorcraft distributors I've bought (3 total) come with notchy reluctor plate bearings. For some reason Cardone tries to reuse the stock plate and when crimping the bearings back on, they seem to over crimp them. This is a problem because vacuum advance may not work properly.
Some pictures added, the silver unmarked weights and arms are the Duralast distributor, the black unmarked weights and arms are the Cardone new distributor. The marked arms (16L,21L) are from the remanned 302 distributor.