B vs A oil pump

31 Woody

31 Woody

Senior Member
I am working on a B engine for my ‘30 Cabriolet. I have a rebuilt oil pump that I believe is an A pump. Is there a unique pump for the B or is an A pump the same? Internet searches and looking at catalogs from the parts vendors does not provide a conclusive answer. Thanks for any help.
 
The pumps can be used interchangeably however to be correct, the shaft diameter size was decreased on the Model-B pump to move more volume of oil.
 
Fit and fuctionally, the pumps are the same. The shaft diameter changed during Model "A" production to increase the volume of oil flow. There are 4 Ford Service Bulletins regarding the oil pump. The shaft diameter change occurred in April of 1928, the pump housing was changed from a forging to a casting in November of 1929 and in July-August of 1931, a shield was added to cover the oil pump when the oil pan dip tray was lowered 1/8".
I have noticed that the oil exit opening near the top of pump housing changed from a round hole to a rectangle. I speculate that the opening went rectangular with the change to a casting. It is not practical to machine a rectangular opening, but it is easily made in a casting.
 
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