Hi guys I have a major dilemma. I have overhauled a 1957 GMC 270. Runs really strong. Had the cam bearings installed and all the machine work done at competent machine shops. Problem is after the engine is up to operating temperature the oil pressure falls off to near 0 lbs. I plasti gauge all the mains and half of the rods. All within specs. I have to admit I was cheap and did not replace the oil pump. The engine sat for many years, but only had 32k miles. I took the pump apart and cleaned it well and in stalled it. Cold start up pressure is 60psi or better. Up to operating temp to zero psi . I also have to admit the engine was on my bench for over a year and I could have missed something or left something. Something is wrong anyway. Have had two mechanical oil gauges on it same result. Any ideas would be most helpful. I will answer any and all questions Thank you. Dave
