The Ford Barn

31 Woody · 08-14-2023, 08:25 AM

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.

BRENT in 10-uh-C · 08-14-2023, 09:09 AM

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.

Bob Bidonde · 08-15-2023, 09:24 AM

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.

Dan McEachern · 08-15-2023, 12:43 PM

Sponsored Links (Register now to hide all advertisements)

Any "rebuilt" pump should have had the shaft diameter reduced regardless of being an A or a B pump.

08-14-2023, 08:25 AM	#1
31 Woody Senior Member Join Date: May 2013 Location: Lake Forest, California Posts: 239	B vs A oil pump 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. __________________ Experience is a cruel teacher. It gives the exam first, then the lesson.

08-14-2023, 09:09 AM	#2
BRENT in 10-uh-C Senior Member Join Date: May 2010 Location: Eastern Tennessee Posts: 11,520	Re: B vs A oil pump 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. __________________ . BRENT in 10-uh-C . www.model-a-ford.com ...(...Finally Updated!! ) .

08-15-2023, 09:24 AM	#3
Bob Bidonde Senior Member Join Date: May 2010 Location: Long Island, NY Posts: 3,470	Re: B vs A oil pump 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. __________________ Bob Bidonde

08-15-2023, 12:43 PM	#4
Dan McEachern Senior Member Join Date: Aug 2010 Location: SF Bay Area Posts: 193	Re: B vs A oil pump Sponsored Links (Register now to hide all advertisements) Any "rebuilt" pump should have had the shaft diameter reduced regardless of being an A or a B pump.