Originally posted by canibalchicken
I completly rebuilt this 1973 350. Crankshaft and heads went to the machine shop. I boiled the block in Lye, cleaned it good and painted it up. I put new cam main and connecting rod bearings in it. New oil pump. It has .040 oversized pistons with gapless second ring. Roller rockers. Dual remote filter system with engine oil cooler. New Lifters.

When I first start it up it has 40 psi Oil pressure then drops slowly to 5 psi.

My first problem was the rear cam bearing was not pushed up against the rear cam cap. I corrected this and changed the oil pump. The plug under the rear main is there.

The fuel pump is blocked off, can I be loosing oil pressure in there?

How does the oil bypass system work? Could this be my problem?

"Dual remote filter system with engine oil cooler. New Lifters".
sure you got enough oil in the pan to fill up all those filters and extra lines?