lifter galley crossover tube

Duane said
Yes I believe this is the post you are referring to B3.
I do not agree that the oil will always move to the low pressure area
And I do not agree that if the oil would move so fast that it cannot make the turn or there would be no oil pressure.
I posted earlier that my number 2&4 main bearings had lost bearing crush after 40 runs.
This engine had the Mopar tube kit in the block full grooved mains,
High volume/high pressure pump like my previous build before, with one exception. I put in an old comp cams cam that had full oiling grooves on journals, 2&4. Why did those two main bearing fail if it was the low pressure area? Engine had 75 pounds oil pressure easily.
I am reminded of an electrical question I once asked.
Why do transformers exist that have redo illusory high voltage. Eg. 600 volts. 2000 volts etc and the answer I was given is that voltage is the pressure. By the time we send the voltage through the wires to the next state or country. We hope to still have 240 volts when it gets to its destination or something to that effect.
We are taking our oil pressure readings at an area that is vary close to the output of the pump. That does not mean the pressure (remember the leakage) is the same at every point in the block.
What are the odds that those two cam journals just happen to coincide with the same two main bearings. Why did those bearings get hot. Why did the required volume of oil not get there.
Why can you not buy a new cam for an La engine that still has those grooves.

Oil (or any fluid or gas) will always move and flow to a lower pressure area. This is the basis of aircraft lift and how an internal combustion engine intake cycle draws in air. Atmospheric pressure is flowing into the lower pressure cyclinders (intake vacuum). Oil will flow to both the crank and cam/head but the majority is flowing to the head since it has more leakage. If the head had a true open oil bleed, say you lost a rocker shaft plug, then the pressure drop at #4 would be even greater, lowering the available pressure going to #4.

The oil flowing in the galley at #4 also feeds the one head. This induces a local pressure drop at the intersection of the#4 crank feed and the cam and head. Mopar designed the cam and head to only be fed part-time. Increasing the flow to full-time with a grooved cam journal or rockers that bleed more oil than stock will further reduce the pressure seen at #4 crank. This could explain your 2 and 4 crank failure, possibly from starvation. Or at least, play a part if oil starvation was the root cause of failure.

High volume pumps are great and they can really work on an engine that has a lot of oil bleeds from large bearing clearances, an oil cooler, turbo, some aftermarket rockers, etc. They only work if you have some of those mods/parts. Otherwise they're just bypassing the excess you're not using to maintain safe pressures. They offer the same pressures as a normal pump but can keep up with extra bleeds whereas a normal pump couldn't.