Oil Pressure Question

[50 F1]

I have owned the motor for years. I bought a car with it in it. Took it out and built a new motor for the car.

Mid 70's 350 Chevy. Nothing special, probably all stock. I have never had heads or pan off.

10/40 oil

Cold start oil pressure is 50lbs

When the motor gets to 185/190 degrees oil pressure is 5lbs

Motor sounds good. No knocks or clatters or smoke.

oil pressure is from a new gauge set, electric.

What do you think?

Would a new oil pump help?

Maybe oil pick/up came off the pump

Any info would be great.
Thanks Mike

[kb426]

What rpm are you pulling those numbers from?

[50 F1]

No tach, but idle around 800rpms warm 5lbs and cold 50lbs

55mph around 2000rpms 30psi warm

[jaybee]

You might start with a different pressure gauge to validate. You haven't said how many miles you have on this rebuild. An oil pump problem isn't out of the question but that's usually sort of a "fingers crossed" solution to a problem that's most commonly worn bearings.

[chimp koose]

10 psi per 1000 rpm is all you need. Could be the by-pass spring in the pump is weak or the piston is stuck partially open .Might be a set of worn bearings. It may also be a cooling system in need of a flush . We ran a 1/2 filled race motor years ago that got the bottom filled half of the motor warm enough to cause the mains to grow and lose substantial oil pressure . How hot is the oil getting ?  I would knock the pan off and replace the pump and possibly bearing shells followed by a good flush of the cooling system . Naturally if the crank looks worn you could plastigage it before replacing the shells.

[50 F1]

I have to tell you what I did, it's been over a year.
I put a mechanical fan on, built a full shroud and put some openings in the side panels. This all helped a lot. The motor is staying cooler an and I am sure the oil is cooler also so I have more oil pressure. All is good. Thanks for your help.
37 Plymouth 2dr sedan slant back.