Are there different castings or bearing lengths out there?
There are but the differences are subtle.
Some of the castings were made "single ended." Looking at the cavity between the front bearing and the gland you may see only a hole where the shaft passes through.
Others have cups/felts at both front and back of the bearing housing.
Others have NO roller bearings but were made to have a pressed in bronze bushing.
Ford experimented with the housing as he went along - and for the aftermarket.
AND there may be differences in the bearings provided. Torrington for years was the maker of these bearings, but now in our "global" world there are MANY suppliers - most of them offshore. And for many the quality is none too good. You may have come upon this problem.
You say this a spare? You may want to try comparing it to the pump in current use. Or for $10 pick up another pump on Ebay and play with it.
You can also check around on the 'net for the original Torrington bearing. It had a number (I've forgotten it off the tip of my mind) and you can attempt to buy a "REAL" bearing for this from the original supplier. The 'net is real good for tracking these sort of things down - Torrington and Timkin are real good at giving the dimensions using online charts.
Hope this helps. The Model A continues to have MANY surprises.
Joe K
