Tractor Repair: Farmall 706 low oil pressure, connecting rod bearing, pressure relief valves

Question
I am wondering what my farmall 706 gas 263 should have for oil pressure. I just had the motor rebuilt by a professional shop. Complete rebuild new crankshaft, rods, pistons, head rebuilt, new oil pump, replaced valves in oil filter base, etc. Currently my oil pressure when warm seems to be low. Warm at 1000 rpm it is barely reading on the mechanical gauge (2nd new gauge I have tried). Warm at 2000rpm it is about 20 psi. I am not sure where to look next.

Answer
Hello,

  Something is definitely not right.  There should be at least 40 to 45 psi at 2000 rpm, depending on what type of oil is in it.  You need to take it back to the shop that rebuilt it and have them recheck their work.  If it's a professional shop as you say, they need to stand behind their work and correct the problem.  If you keep running it that way, you'll be doing another rebuild.  There are alot of things that can cause this problem.  The clearances between the rod and main bearings and the crankshaft need to be checked.  I have seen bearings packaged wrong with incorrect sizes marked on the boxes, connecting rod bearing caps installed wrong, oil passage plugs missing from the engine block and crankshaft, crankshafts ground incorrectly, oil pressure relief valves installed backwards, etc.  Everything needs to be rechecked because something has been forgotten, overlooked, or done incorrectly.

                   Good luck,

                        Arnie