I was wondering if anyone else has had this issue? Just rebuilt a 350 and it runs fine, but the oil pressure reads only 15 lbs. I've used the stock gauge, a mechanical gauge and still it reads 15 lbs. Oh, and that's when it's at 1000 RPM! When it warms up and drops down to idle speed... [zero] oil pressure!
Needless to say I'm not even starting it now, but I can't figure out why the pressure has dropped so low.
I'm running standard 30W oil. Standard filter. It has all new bearings for the crank and rods. New oil pump. New cam.
It just puzzles me to see the pressure so low. I even tried adding a few extra quarts in case the pick-up screen was low... nope. Didn't help a bit.
The oil filter uses a adapter to run the oil through a cooler inside the radiator and I check the bypass value in that adapter too. It seems to be working correctly. I've never seen this before, just wonder if someone else has... and knows what's wrong.

Did you use Plastigage or anything to check the bearing clearances? You might need to install .001 or .002 undersize bearings to lessen the clearances, which will increase your oil pressure....good luck, George

As above, also check position of pumppickup screen, may be too high and miss the oil or too close to bottom of pan and oil can't get in, at times they even fall out, screen should be 1/8" to 1/4" above bottom of sump.Checkpump drive. Check for missingoil gallery plugs. Machine shops take themout to clean out the block and then forget to put them back in.

Thanks guys. Yes, I did check the bearing clearances with Plastigage and I was around .002. The pick-up screen is set correctly, I double checked that prior to install.
However, the oil galley plugs? I'm interested in that a bit more. Can you expand with more details as to their function and location. The shop that cleaned the block left out all the plugs and I was sure I found them all. But, maybe not.

There are 3 oil galleries, one on top of the camshaft and 2 on the sides. If I remember correctly they have plugsat each end, the back ones are on the outside of the block, the front one are under the timing cover. There may be others, as they are needed wherever an oil passage was drilled. As I said, I am not sue of the locations.

Yeah, I know what your talking about. I have plugged all those holes, front and back. Somebody mentioned once that there was a plug or value in the block under the rear main cap. Do you know anything about that kind of plug?

I'm going to start swapping out parts like the oil filter adapter, pump, etc.

Is this what you are talking about? Plug uder rear main cap.

There is also a plug on the deck surface at the driver side rear

Yeah, that might be it. What do you know about that? What's the plug called? I couldn't find it on the factory list.