It was always my understanding that after blocking the oil at the #1 main oil passage on the right oil gallery the oil would have no place to go except to the #2,3,4 mains and then the cross over tube would feed the left oil gallery and the #1 main from opposite direction. Which kept a constant flow of oil to the causal #4 main and #5 and 6 rods bearings. I have done this mode to all of my small blocks except one, my first one a 340 that starved #4 main and spun 5 and 6 rod bearings at 7500 rpm's. Since I have used this mode none of my engines have ever showed an oil starvation problem, lucky maybe but at this stage of my life I will stay with what works for me.
