Brother has a 460 that has an oil problem that is new since rebuild last summer. The pressure starts off at 55psi. at idle, but drops as rpms increase. He says it drops down to 35-40psi, then he backs off the gas for fear of funky chit happening even though still plenty of press. As soon as the rpm's are brought back to idle, the oil press. goes back up. It follows the rpm, not the temp. Makes no difference if oil/ motor is cold or hot, same pattern.

9 qt oil pan, oil level is fine. new oil pump. oil cooler, lines are plumbed correct, but I think they are under sized. 3/8" ID. BUT, it has ran fine for last 7 yrs with those lines. Mechanical gauge. Same results with a different gauge. Reading is taken from the back of the block where it always has been.

Ideals?
Thanks

I agree about the undersized lines. Ford pumps are geroter, not vane, so I would suspect pulling air in the pan. If it is a stock block and the top end is not restricted (with sleeved lifter bores), they like to push a ton of oil up top which drains the pan quickly.

A simple test would be to add an extra quart or more and see of you gain any RPM before the fall off.

I switched to restricted SVO blocks and this problem went away.

Yes, stock block. He added to the oil pan capacity thinking it was starving for oil by extending the bottom of the pan length more. The depth was not changed any.

What is geroter?

Thanks

Considered by many to be a superior geared pump. Many aftermarket pumps are Geroter pumps. Two gears draw the fluid into the pump.

I know it is a hassle but the best fix to a stock block is lifter bore sleeves. It is only necessary on the port side, you can restrict the starboard side oil gallery. Stock blocks are good to 700-750 horsepower if this is dealt with. 70psi is maintainable

I am confidant your brother is sucking air.