I prime one of my stock unbush motors with the valley pan off, the lifter bores on most stock Mopar block leak a large amount of oil from them, A BUNCH
Those stock type blocks converted to busing with don't
In my opinion, after having one roller valve spring break years ago, allowing the lifter to be pushed out and cocked high enough in the stock lifter bore to unshroud that oil galley losing all pressure at 5600 RPM in high gear
My goal now is to have every stock block bush that will get a roller cam in it