In my case I did more than cut a shallow groove on the back side of the bearing. I actually removed all the material between the two holes to create a slot. My theory is oil should now be allowed to flow 100% of the time instead of only 25% of the time as the old cam had a groove cut just 1/4 of the way around the circumference. Maybe that was the engine's oiling problem in the first place as I found melted babbitt throughout the engine's oil galleys with all the bearings gone except the rear cam bearing which I reused.
