Dosen't the pump bypass simply empty back into the pan? in which case couldn't a clogged filter end up starving the top end -and everything else? If there is another bypass, sounds like my problem would be lifters full of babbett. The reason I came up with the clogged filter idea is because at one point, I checked the oil level and found it to be almost nonexistant on the stick -so I checked the oil filter housing and found it so full that a fair amount came out upon opening the lid. I let it sit awhile for the level to go down and then replaced the filter with a new one.

Since I mic-ed each rod journal across multiple quadrants to find any damage and determine which bearing sizes to order, I saw plasticgauging as redundant, as it would require my using -and possibly damaging -the new bearings anyway, as the old bearings were mostly melted and totally unusable for plasticgauging. Also -we are talking about my running the engine for at most a total of half an hour since bearing replacement -I sincerely doubt any variance found between plasticgauge results and multiple millimeter caliper readings -to the third decimal place -would be the cause of the severe noises I am now experiencing.