I combed through this thread, some good ideas and some I question.
The biggest question comes from the idea that the #4 main is starved as the oil prefers to fly past the feed hole....this is pretty dubious (as others already noted).
The desire of oil to go past #4 would pretty much be the same as it would for #2 and #3 if that were the case. Additionally, if there is 60PSI (or whatever) within the system, that pressure tends to exist independent of flow. In other words, if there is 60PSI at the #4 oil feed hole, oil is going to want to pursue the path of least resistance and go down that hole. It's not going to keep trucking past so that it can join the fight of maintaining 60PSI elsewhere. The oil will prefer to go straight past #4 if it's a no-pressure situation. But as soon as you pump more oil into the galleys than can escape, you begin building pressure and the oil is obligated to find someplace it can go to escape, even if it has to take a right angle turn.
Here's my question...I've read tons of theory, but no one has admitted to actually tapping a pressure gauge into #4 to read what's going on. Who has done it?
I also wonder...rather than letting the oil go to the mains then back up to the cam bearings (#2/#3/#4), what if you blocked it and fed those three bearings in the lifter valley using small tubing?
