Engine in question is newly rebuilt 368 Y-block (56 Lincoln). I just built up the engine and it overall it runs great, with the exception of nearly zero oil pressure at idle after it gets to operating temperature. Running 30w oil, at cold start-up oil pressure will go to 50-60 psi. Upon reaching operating temperature I will get 0-5 psi at idle 750 RPM. (At 1250 RPM it will go up to 10 PSI). General info and other things I have tried:



1 - I confirmed the pressure reading with 2 different direct read oil pressure gauges (not electric).



2 - Changed the oil pump, but no difference in behavior



3 - Verified crankshaft bearing clearances. I re-checked a rod and main and both came in at around .0026 . Service manual calls for acceptable tolerances of .0007 to .0036 so it appears bearing clearances are with range.



HELP I need:



1 - Could Cam bearing clearance be suspect? Would that potentially cause this?

2 - Only other major machine work that I had to be done was 2 cylinders needed to be sleeved. Could that have breeched an oil gallery? If so, I would assume that it would be sealed back up with the new sleeve.

3 - I do not believe the oil pump is sucking air, due to no oil pressure fluctuations or air in bubbles in the oil.



ANY help with ideas or past experiences would be greatly appreciated. This one has me stumped.



Rob