Oh man, how embarrasing. (Uncle Tony/Nick's Garage)

No way I would have run that engine up to 5000 with that oil pressure. Something was obviously wrong and adding revs wasn't going to fix it. I've run across those same symptoms before where someone put in standard bearings on a .010 under crank. Great oil pressure when cold, but, soon as that oil heated and thinned a bit, the oil pressure was crap. I didn't watch the mega video where they built the engine, so, maybe that was already eliminated as a cause. I find it hard to believe it could be anything in the lifter area causing that sort of oil pressure problem unless an oil gallery plug is missing or something similar.