When I had the "brain" issue and was trying to find out why I didn't have oil pressure, I actually swapped out the oil pump for one i had on the shelf. It was an early, aluminum, narrow rotor pump and had about 50# at WOT and 20-25# hot at idle. But I had the original pump that was mated to the cam in the truck; so yesterday I unbolted the RH motor mount and jacked the engine up a smidge. I removed the aluminum pump and installed the newer wider rotor pump that went with the camshaft. Fired everything up and took it for a ride. Allowed temp to get up to about 200 degrees so I know everything was hot. Checked my pressures and had about 52# at WOT. But my idle pressure was up at about 35#. I am guessing the wider rotor pushes a little more volume at idle than the aluminum pump did. Now to find that pesky rattle I hear every once in a while!
