My take on the oiling system crossover tube for the small block

CMcAllister said

I agree that the timing could have/has something to do with it. That and the direction the oil has to move through the crank vs. centrifugal forces. However, I've tried full groove bearings, cross drilling cranks, etc with zero benefits.

Another issue is the timing of the passage in the cam journal lining up with the block passages vs. where the crank is as far as the rod/piston being under a high load i.e. on the firing stroke. Does a 1/4" hole suddenly opening from the main saddle all the way to the head cause a quick drop in pressure just as the load on the rod bearing is greatest?

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Oh I never disagreed with him on the issue. Only on how he chose to address the problem.
An observation that I made to him was that my 1969 340 never had the large counter bores machined into the bearing saddles like most newer blocks do. I can only assume that either my block missed a machining operation during manufacture my theory is that Chrysler became aware of the issue and began adding that counterbore to the bearing saddles to address the issue. As you have said, below 3000 rpm not much of a problem, but at high rpm combined with slotted bearings that Mopar performance used to sell you have shifted the timing of when the oil hits the bearing. Your comments
about the cam timing seems logical too and makes the case to restrict the flow of oil to the cam bearings.