Oil Pump Volume

[JV Puleo]

I am designing an oil pump for my 1910 Mitchell because I'm not comfortable with its semi-total loss oiling system. Neither was Mitchell, because discontinued the use of the separate oiler in 1910 and went to a plunger pump in the sump... but I don't have the 1911 sump, and it isn't interchangeable with the 1910 crankcase, so I'm working on a separate, bolt on unit that will run off a cam on the back end of the camshaft. What I can't find is the optimum volume... for instance, a plunger .875 in diameter with a stroke of .250 will move .150 cubic inches of oil per charge... an quart is about 57 cubic inches so, with a pump that size, will move 37 cubic inches (about 2/3 of a quart) per minute at 500 rpm. The sump holds about 3-1/4 to 4 quarts, so all of the oil would pass through the pump every 5 to 6 minutes. I'm wondering what the volume of other pumps may be. The 1910 REO I had many years ago had a plunger pump in the sump with a stroke of about 1/4 inch but I don't remember what the diameter of the piston was, though I suspect it was about 1".

 

[Guest Rp1967]

A small gear pump a little larger than you think you will need with a 30 psi relief ( give or take) and you can put an orifice in the pressure line if the volume is too high as a restrictor.

Without knowing how well your engine returns oil to the pan , I couldn't be more specific.

[Mark Shaw]

My 1913 Buick has a total loss system & uses less than a quart every 100 miles with a 201 cu in 4 cylinder engine.  By your calculations, I think your proposed pump will be overkill.  The piston sizes and stroke on most mechanical oilers is very small (measured in drips per minute for each bearing location).  My Buick uses a single sight glass that gravity feeds the main engine bearings and the book only recommends 3-4 drips per minute.  So, I suggest you calculate the number of bearings to be lubricated multiplied by the amount Mitchell used in their older engines to determine the size of the pump you need.  Then add maybe 20% for future bearing wear.