Oil pressure issues this maybe some of the problem.
 

I have seen on all GM rear caps SBC & BBC we have found then to be restricted because of the casting hangs in past the oil port of the oil pump and we have seen some that have been block 60%

Take a oil pump cut it off like the one on the right.

The cap on the left has been opened up to match the oil pump.

The cap in the middle had been marked with a marker showing how much has to be removed.

The cap on the right you can look in the oil port and see the casting blocking the port.

Even on the after market blocks they some times have to be touched up.
http://i7.photobucket.com/albums/y27...REARCAP003.jpg

Good tip Carl, :idea:
I would venture to say that 75% of the people who bolt their own engines together donot even look at this. I first started grinding,polishing and radiousing the oil intake hole going up thru the cap and matching the Main cap pocket about 30 yrs. ago and still do it today. I use impression bluing to find the outline of the pump pocket.

Zip.

Actually, I have always done this on my motors.

Very good tip for those who don't do it!!!

TS1955

x2. Oil is the blood of an engine.

Dave

Do you use a copper gasket in between? I never did until my last engine had a leak inside from a oil galley, and when i checked it did not seal 100 percent between the cap and oil pump. So i made one from a old bbc copper head gasket.

Thats a good idea too, somebody should market a thin aluminum or copper gasket just for this.

You can get those gaskets through Jegs. They are designed for one use, and are pretty cheap. Great idea if you ask me............My engine has them.

Mark