I have a newly rebuilt '82 Chrysler 318 in a 1934 Plymouth 4 dr. sedan. It has about 2000 miles on it. I noticed early on that the electric oil pressure gauge was showing only about 5 psi @ idle after the engine was hot. ( showed 20+ when cold). After engine break-in period I went to a heavier 20W50 oil and it was a little better. By the way, it shows 40+ at speed when hot. I finally put a mechanical gauge on it just to see if the electric gauge was off, and it shows almost zero psi at idle when hot. All bearing clearances are well within factory specs (everything was plasti-gauged on assembly). It has a new Melling oil pump. I pulled the valve covers off thinking maybe the plugs came out of the ends of the rocker arm shafts, thus limiting the restriction of oil flow, but they were fine. Anybody have any ideas before I pull the oil pan off (which isn't too easy of a job in this car) ? Thanx