Now this is were it gets really intersting - especially for me!!
The only thing I know for sure at the moment is that the supplied flange in the kit is 3/4". Everything else is now in something of a state of confusion for me.
Here's why -
Decades ago I rebuilt the water pump and the only bearing I could get at the time was one which had a 3/4" shaft the whole length - pilot, flange and impeller.
Now I do positively remember enlarging the pulley hole [double groove and possibly not original to this car but is the subject of further investigation] and the fan extension [definitely not the original] to suit the 3/4" shaft. [even the fan was a 6 blade therefore not original]
These were easy to modify as they are not precision
interference press fit, although still have to be carefully sized and centered anyway to be a snug push-on fit with no run-out.
But for the life of me, I cannot remember enlarging the flange hole, or the impeller hole. But maybe the flange hole was already 3/4", hence my question to John asking to clarify exactly which part of the shaft was 3/4".
But then what of the pic in the ebay auction, showing a shaft that is 5/8" the whole length and the seller saying he can't get that one any more and is going to change his pic to show the one that is now in the kit.
That would suggest that the originals were 5/8" for both flange and pilot. In fact I've pulled another bb pump apart and that's what it has, a 5/8 shaft and 5/8 flange, and the same for many other small block pumps that I have kicking around.
But then what about the impeller, that would have required me to set it up in a 4 jaw chuck, muck around with a dial indicator getting the original hole running true [though not quite as critical as the flange], then machining it to an exact press fit.
Futhermore, the surface finish in both the flange and the impeller is a very bright polished finish. I don't think I could have got that kind of finish using just a lathe - I don't know - I don't remember anyone I knew that would have had a lathe - I certainly didn't have one....I'm not even sure what city I was in at the time!!!
[dammit brain, why can't you remember!!]
So at the moment I have a mix of bits that I'm unsure of were they came from, or how they got the way they are....