IMHO your first mod mentioned is correct. The reason their is confusion is that it is not universally understood that there are two widely accepted methods to the small block that both address the same issue. That issue namely to slow down the oil velocity in the passenger main galley so that the number four main bearing will oil properly is not totally understood. There also has been another "new type" of crossover tube that is being confused with the original type crossover tube.
The new type is to address the oiling to the rockers and the original was to address number 4 main bearing.
There are some on this thread including the original poster who know the mods but not the reasoning.
I recently purchased a fresh copy of a book that was published back in the late 1970 s at the peak of small block oiling development to make sure that I was understanding this issue myself.
The book discusses both approved mods with the issue being number four main bearing starvation caused by excess oil velocity in the right side oil galley.
To understand better, your car has a hard time making a sharp right hand turn at high speed, but has a much easier time if you slow down first. This is what the oil in the galley is being asked to do, to feed the main bearings. After the oil comes out of the pump it goes into a straight run in the galley at high speed and mostly goes right past the first turn which is number four bearing. Also, number four is being asked to feed your rockers way up on top also at the expense of the crank bearings.
The addition of the other crossover tube discussed in the " how to build big inch stroker small blocks" will allow number 2 and 4 cam bearings to be restricted as well because the rockers are now fed directly by the new crossover tube and not the main bearings.
My new build will contain two crossover tubes as well as bushed lifter bores that will be pressure fed with a .030 feed hole.
Hope this clears the issue better.
Duane
