The Larry atherton of A&W performance article in the "Petersens complete book of engines #9" said that he had seen many rod issues on either side of the #4 main so what he did to try to get to the bottom of it was shoot water in from a garden hole in the block for alot of experimentation & he came up with the conclusion (right or wrong) that the water (& therefore the oil) was rushing by the turn to the #4 main too fast to make it & that the bypass over to the other side took care of it (by reducing the velocity). it had some other good seperate from oiling info & was well worth the few bucks I paid for it "used" off of eBay.
