[Y-Blockhead]

Originally Posted by Doug in NJ

The "A" oil pump, like almost all of them, a constant-displacement design. Normally the pressure is so low only because nothing is resisting the flow of oil. If the oil must be forced through a filter, the pressure will rise. If the filter got all clogged up, the pressure would rise quite a bit.

Doug

Originally Posted by BILL WILLIAMSON

Model A oil pumps are a very conventional design & flows gallons of oil per minute. They have NO pressure regulator valve, thus, the pressure is low. They have great flow to fill the oil chamber & the baffle plate in the pan, as all the lubricating is done by dip or gravity flow. I read that the pump is CAPABLE of something around 80 PSI. With the proper plumbing, they ARE capable of pushing oil through a FULL FLOW filter.
Bill W.

Originally Posted by colin1928

I once tested a rebuilt stock A pump with drill and simple test rig it flowed 10 litres per minute with no restriction at 1200 rpm drill speed
The same pump also made 93 psi when closed off when the drill was not able to keep turning
a stronger drill may have made more psi ???
Colin

I have said it before on Ford Barn, as have others, the Model A oil pump is a positive displacement pump and will put out enough pressure to flow thru a filter, even one with a 12 lb. "check valve". The reason in stock form you don't see a higher pressure is there is no back pressure on the system, it is just open ended into the valve chamber.

There is a new video on YouTube stating what is written above in other posts and it is simply not true and there is no need to drill out the valve.