TEA 20-80 Oil pump

I have finnaly got to the point of reassembling the engine for my 1950 TEA. I started the project because of very low oil pressure when the engine was warm (some where between 0 and 2 psi). As it turns out a lot of the problem was a previous rebuild, the crank shaft had been turned 10 thou under and the main bearings were sized properly but the piston rod big end bearings were standard size (i.e. 10 thou too big). So I am at the point of reinstalling the oil pump. I decided to check the pump against the specifications and no suprise, it is worn. The question I have is is it too far gone? The clearance between the outer rotor and the housing is between 8 and 9 thou, the outer rotor depth is 2 thou under size the housing depth is 4 thou over size (a total clearance of 8 thou) and the rotor clearance is 6 thou (max spec 4 thou). So do I replace the pump, are the replacement pumps any better than this? I can tighten some of these dimensions, I can lap the housing and reduce the 8 thou clearance, but I can't do anything about the clearance between thr outer rotor and the housing or the clearance between the inner and outer rotors.

Thanks in advance

Al

I cam across this situation, after a back yard overhaul. Are all Journals still round? Have you checked the diam. of ALL Journals, with an OUTSIDE MIC.( MIC.CHECKED against a STANDARD)? I was looking into low oil pressure on a Perkins engine. It had unacceptable Journals after running with in correct Bearing shells.
Bob..

As an owner of 2 standard motors tractors with each having low pressure after warm up I'm starting to believe its more than bearing clearance. Mine will peg the gauge cold and yet go to 2 lbs hot. 180 degrees should not affect any component that much especially a pump that's capable of 80 lbs cold. Mine is not the mains clearance, stopped up screens or oil galley,relief spring, engine temp.So let me know what the fix is.

The crank shaft was checked by an engine machine shop, they do very nice work.

Al

Between inner and outer rotors Ferguson specifications are 0.001”- 0.004” as maximum allowable wear .
New pumps bought here in Australia have tolerances greater than this when brand new ! and are hence worse than useless and the cause of much disappointment at first start up of a rebuilt engine.
The rotors from a USA built Chevrolet Luv 1600cc oil pump are reputed to fit into the housing and are made to finer tolerances but I can't guarantee this .

Does your have the oil pick up tube with the rubber seal at each end?
Warms up and sucks air?
TO-20 has this set up.
Engine currently has about 80 hours on it and O/P is constant around 40 PSI hot/cold/idle/road speed

Have you read on page 2 of this forum where Hoopy Cuztom has the same problem? Bill Bronx has a fix in there and there's also pics of the filter guts. Let me know if your tractor filter has missing or parts installed wrong. THANKS