lifter galley crossover tube

I think we've gotten a little off course. Duane, I believe your 2&4 failure was from little things that added up to the failure. Your full groove cam without a restriction in the rocker pedestal played a part. I'm not sure about the rest of your combo like the pump, oil type, bearing clearances, etc.

Now, the oil tube mod and plug has one purpose, to take pre#4 and dump it into the other galley. Some say, as in the guitar jones oil mod write-up, that this slows down the velocity of the oil flowing by the main 4,3,2,1 ports. This will allow the oil to take the 90* turn towards the mains easier. The entire oil galley will now dead-end at #1 and the oil pressure will allow oil flow out the leakage areas in the crank/rod. The more oil leakage you have that is connected to anything that feeds the crank will drop the pressure at the crank. Full time, unrestricted oil to the head is a bigger leak compared to the crank leakage. this induces a greater pressure drop for the crank oil supply at #4,2. Not to mention, the lower pressure that the full time head oiling creates, will allow the oil to flow to the lowest pressure area, the head. This seems to be a problem when you want to rev higher and higher. Even tho you did the tube mod, the head oiling screwed you over, IMO. A restricted head would lower the pressure drop seen at the crank/head oil port intersection. That, and/or make the crank/rod bearing clearances larger. This will allow more flow past them, in turn changing the pressure drop at the head/crank intersection in your favor.

What I was pondering about using an oil cooler had nothing to do with using the tube mod/plug at all. My theory was that if the sole problem is the velocity of the oil flowing past 4,3,2,1 is great enough that it is difficult to make the 90* turn, why not slow down this velocity by dropping the pressure/flow by running a line to an oil cooler coming from the oil pressure sending unit connection. Dump this line into the pan. No tube, no plug. On second thought, the plug creating the dead end at #1 is equally important (if not more important than the tube) to this mod because the oil flow becomes much slower since it doesn't have to feed the other lifter bank at #1. The tube simply helps slow down the oil by feeding the other lifter bank before #4 as well as provide lube since its passage is now blocked by the plug in 1.