Redog

1968 350?

I replaced the PCV valve and runs at 50 psi when I first start it but dropps to about 25 to 30 while cruising at 3000 to 3500 RPMs after the motor is at the operating temp (180* thermo if needed to know)

Drops between 8 to 12 at idle (750 RPMs)

Sounds about right to me, and it got better after replacing the ORGINAL PCV valve, but I figured I'd ask the pros here.

I have a pretty decent leak at the oil pan, I lose about a quart appox every 600 miles, and I'm getting the pan gasket replaced soon when I get the tranny rebuilt, hopefully within a month. I figured I would get the oil pump replaced if needed. As far as I know, it's orginal

Oldsguy

Not sure if replacing the pump would improve your oil pressure all that much. I know they make "high pressure" oil pumps but isn't most of your oil pressure developed by the bearing clearances in the mains and rods? Your oil pressure sounds pretty good for an old engine. About the pcv valve contributing to the oil pressure, interesting. I thought the internal atmosphere pressure wasn't the same as the oil pressure. Hmmm, not sure.

Redog

^^ I didn't know the oil pump didn't contribute to the oil pressure.

After I posted it I re-read it and thought the same thing, for a 40 year old motor, oil psi is pretty good

Oldsguy

Well, I really didn't say that. There would be no oil pressure if there was no pump to put the oil at the bearings to begin with, can't have oil pressure without a pump, but you won't have good oil pressure with old bearings either. In an old car, the reason for low oil pressure is probably going to be worn bearings.