I have a new rebuilt motor 69/390 bored 60 over, balanced, ported 58cc heads, comp cams 280h, push rods, lifters and springs with scorpian rollers.
Everything is new in the motor except for the crank, and the timing chain cover. I replaced the oil pump gears, checked the walls of the pump and they seem to be fine. I am considering replacing the timing chain cover to see if that will make a difference. But if any of you have experienced this problem, please let me know. I would hate to have to tear this engine down.

Car runs fine down the road but once it gets a little warm the motor loses oil pressure. Also there is no knock or lifter noice when pressure drops off. And the oil pressure is at 0 at an idle in gear, and goes to 20 when you have it in park. I also changed oil pressure gauges.