Discussing my engine build with Fred Apgar, he suggested cutting a small chamfer on back of the crank bearing shells. He indicated this was done on race built engines to improve oil flow.
I got out the old bearings today to see how difficult this was. Using a new 118 deg drill bit (9/32") it was very easy to lightly chamfer the backside. I was initially concerned the drill bit would grab and self feed, but with this large a bit it's very easy to control. There was more chatter in the cut than I liked, so I tried a small carbide Burr by hand and it left a very smooth finish, and took almost no pressure to form a chip.
My case is still wrapped up and clean, are the oil feel holes only on the bottom case half?
