Oil cavatation cauised by a 3/4" pick up is a new one. The following is where that theory came from.
There will be oil cavataion beneath the screen if the pick up screen is less than .375" from the floor of the oil pan. That happens when a HV oil pump is installed in a engine with a stock depth oil pan. High volume oil pumps have 0.300" longer spur gears, a longer and thicker housing, 3/4" pick up tube and a thicker bottom plate. That makes those pumps 0.587" longer than a stock oil pump that has a 5/8" tube. If you only have 0.375" to 0.500" clearance between the screen and bottom of the pan with a stock oil pump, then subtract .587" for a longer HV pump, as you can see, the clearance becomes critical. Optimum screen to pan clearance is between .375" and .500". The easiest way to measure is with a carpenter's square from the block pan rail to the bottom of the screen after the pump is installed finger tight. Then compare that measurment against the pan depth from the pan rail to the bottom of the sump.
There are dozens of different styles and depth oil pump pick up screens available from Moroso and Milodon but buying those pick ups through trial and error can get expensive. After purchasing four different Moroso pick up screen assemblies, I finally gave up on aftermarket pickup assemblies. I shortened a stock 3/4" pick up tube 0.500" and it fit the longer Melling Select 10552 oil pump and stock oil pan with 0.450" clearance.
This is why Moroso offers HV oil pumps, pump pick up screen assemblies and a special oil pan in a kit which is supposed to eliminate most of the guess work.
Last edited by MouseFink; 03-03-2011 at 01:55 PM.