Here is something that was posted years ago.
Quote:
Drill and tap for 1/2" pickup. Drill hole below threads to 11/16" and 2.94" deep. Drill pickup hole at pump mounting surface 5/8" and 1.56" deep, radius and deburr the intersection point. Drill pump pressure hole to gallery 9/16" and 7.62" deep. That will convert to Hemi oiling system. This page 270 and 271 of "Engine speed secrets & racing modifications for Chrysler V-8 engines" Eighth edition. Part # P5249010.
And this is my 2-cents (similar):
When I do the 1/2 NPT conversion, I drill the entire passage from the pickup 5/8" dia. Then I drill 11/16" dia, 1.25" deep for tap clearance. Then I drill 23/32" dia before tapping, the depth of the threads on the pickup.
I also drill 5/8" dia the connecting passage from the pump side, and clean up the intersection with a long carbide burr on a die grinder.
While at it, I ream the passage from the lifter galley to the main bearings 17/64" (9/32" is fine too).
