lost oil pressure

[sledge33]

yesterday we started my engine for the first time.i bought the engine about three years ago from a machine shop and it had been rebuilt.the engine sat in my garage until i installed it in the car before it went to paint and i never got it running.the car was at paint hell for over a year.now that i got the car back we were going to get it running yesterday.everything was going good,we primed the pump with a drill and got 60lbs of pressure, and so we started the car and the oil pressure was around 70 lbs.we let it run for 15 min at about 1500 rpm. when we went to idle down the oil pressure went down with it,all the way to 0. we shut off the engine and checked temp because we didnt think the temp guage was working. the engine was still cool to the touch.we would start it back up and oil pressure would go to 20-25lbs and slowly drop over 10 -15 seconds, i dont know if it would drop to 0 as i would shut the car down when oil pressure would drop.
any ideas?
since it sat so long could it had some rust to clog up filters?
the engine oil was clean when i drained it.
i was told the plugs behind timing chain may have came out.
any help is appreciated.

[Vegas69]

Oil pump pickup may have fallen off... Dumping an extra quart of two will verify. Just don't run it long.

[sledge33]

if the pick up fell off then it wouldnt have any pressure would it? when i go to restart it i have about 25lbs and it drops over a 30 seconds,dont know if it will drop to 0 but pretty sure it would because it did the first time.

[ma73z]

We had a big block on a dyno that did a similar thing. Not sure what you're running for an engine but this might be something to check out. We found that the distributor (cheap knock off) was made improperly, the housing was machined to small and allowed the oil pressure to bleed off between it and the block. The pressure was fine as long as the rpm was up but as soon as you started backing off it started to fall.

[Vegas69]

It would have oil pressure for a little while until the oil pumped out of the pan.

Ma7 makes a good point as well. Some distributors have orings tha MUST be used.

[MarkM66]

Did you get it figured out?