[Sun Tuned]

All that junk out of the way, they tried several different things on the shafts to “direct” some trace amounts of oil up to the base of the top bushing. The biggest expenditure they made was a series of spiral grooving at the top end of the shaft just under where the top bushing is.
This deal lasted about 2 maybe 3 years and then you never saw it again.

This business of oil being “sprayed” upwards from the bottom of the shaft is nonsense. Theres none there , not even any decent amount of pressure at that interface anyhow. So just forget that idea.
There is a fair amount of splashing going on around that bottom bushing though, and this was used to their advantage at the bottom to lube it.

There is one situation I will mention that causes oil to pool in the top bowl of the housing… if you have a clogged or inop pcv system or your engine has suddenly developed a severe crankcase pressure event, oil can and will be forced up through the top bushing and puddle inside the bottom of the distributor housing. It is important to note distributors do not suck oil but they can be pressurized to move it up there. This is a bad deal and not a normal occurrence.

So the only thing lubing that top bushing is the little bit of base oil in that grease packed in that 5 cavity well at the top.

And folks have tried all manner of stuff at the top. Ball bearings, needle bearings, bushings , just all sorts of stuff.
Ball bearings are good for a radial application such as a water pump, but not the best for a distributor. They found that as simple and archaic as a lowly bushing is, in the end game a plain old bushing is really the best deal to put in there , as long as it’s not run out of lube or severely undersized for the application.

There will be some folks come by here in a bit and argue this point but that’s fine. I’ve seen the GM data on this, it’s not quite as glamorous for the ball bearing as you’d think. Plus as it ages out and starts to degrade the “junk” that gets produced in a sealed bearing… stays inside and helps to create more junk , faster still.

As far as bushings are concerned, the last ones GM did for the large cap HEIs in Chevrolet was the chrome looking outer jacket, that may be a sintered iron material I’m not sure… I do know when you put a couple of em on a hot plate the oil comes out the middle of the bushing ends and most assuredly NOT from the outside of the chrome plated outer jacket. This tells me if it don’t leak outside the jacket , you not readily gonna put it back in through it either. That’s why they drilled the 1/16” holes in there .

This aftermarket copied stuff… whatever they make the bushings out of , the inside finish of them reminds me of looking at an old style fresh pair of full metallic brake shoes. And when worked I can tell you they just don’t quite spin as free and smoothly as the GM distributor does..