I can't recite measured clearances at this point but I remember being satisfied with how it measured out. I went all out on machine work, done by a machinist I have long confidence in . I installed dry bearings to torque settings and snap gauged and measured all. Crank thrust and rod side clearances etc. I also plasti gauged dry rod and mains prior to final assembly. Maybe I missed somewhere...but was very careful and in no hurry. I've experience in building motors.
I am thinking I need to remove the motor and inspect, only reason I hesitate is that I easily achieve 40+ lbs of working pressure with motor at temp. If oil pressure was half that and then dropped of at idle I would be sure of a clearances problem. Just seems to lose prime at idle speed, even then it doesn't completely drop away unless a bit of a sharp stop. Like the pick up un-covers. Pickup tube and oil pump mating surfaces are flat and checked.
My 54 uses a short production 223 oil pump, using a round drive having flat key ends at both the pump and distributor ends, also using a long tube pick up that mounts to the side of the pump. Each rebuild interval I have reused the original pump.
I had to make a bottom plate gasket at this last rebuild and it was half again thicker than original? Funny how hard a guy can reach doing diagnostics, experience has always shown answers to be straight forward....smile.
Didn't realize there was a oil pump – distributor conversion that was workable. I've always strive to keep this truck all original, it came to me having never been apart. Maybe time to get on the bus.
Again, thank you very much bubba.