Hey guys need to bring some closure on this one:
1) In the beginning
oil pressure was 50 psig at 4K rpm and would drop to 42 psig at 6rpm. Engine lived like this for 5K miles.
2) I adjusted rv spring in existing Mellon 1083 hv
oil pump.
Oil pressure went to 57 psig at 4k rpm to 52 psig at 6K rpm. This was a huge score and proved the oil pump was bypassing the whole time!!
3) Replaced rod bearings - zero change, old ones were perfect as were new ones LOL!! main bearings were perfect but found Cleviet HX on the end indicating an extra .001" clearance on standard shaft. This lead me to believe engine was built with larger clearances. Who knows I do not trust plastigauge and had no way to determine. Builder either didn't have the bearing clearance informatio or refused to provide them to me. Their recommendation was 15W40 diesel engine oil, WTF!!!!
4) I bypassed oil cooler - zero change
5) Pressure drop across oil cooler plumbing was found to be 10 psig. Very interesting when I put oil cooler put back in circuit pressure drop did not increase across oil plumging and cooler circuit (standard Superformance set up)
As it stands know through exhaustive efforts I did some oil testing. Initially had Mobil 1 10W40. Went to Brad Penn 50WT. Oil pressure was 62 psig at 4K rpm and 58 psig at 6 Krpm (used to be 58 psig at 4 krpm and 52 psig at 6k rpms with previous oil). Got bored and tried Brad Penn 20W50 for cold start-up protection and oil pressure stayed at 62 psig at 4k rpm and 58 psig at 6 Krpm at 100C. I know the 50WT is a better lubricating oil blah blah blah but I wanted to minimize wear on start-up even though I am in Texas and the car rarely sees sub 60F temps since I start it in the garage.
In the end I honestly feel there is a venture effect somewhere on the block tap for the gauge or as noted earlier in the thread there is Teflon floating around in there as I dug a bunch out of the pressure gauge port. earler The engine internals are immaculate with zero wear, zero oil consumption, zero noises etc. I have run the living sheet out of this engine call it BFI testing (brute force and ignorance) if there was an engine issue it would have gotten worse.
I don't think anyone has an issue with 58 psig oil pressure at 6 k rpm and that is how the story will end. I seriously doubt the cause will ever be determined. Proof is in the pudding, engine has lived for over 5K miles with original owner and he only had oil pressure of 42 psig at 6 krpm!!! As Keith and others have said doesn't really sound like a problem!!
Got my motor mounts installed from Oltoff, they are a work of art!!! Polished my wheels over 8 hours, they glow like a mirror, next time I will contract that out as my finger nails are still growing back, LOL!!! I out did myself on those. Original owner never touched them in 5 years!!! It is nice to start and finish something.
Probably pull side pipes and headers off and get new ceramic coating. Once that is done the car will show as brand spanking new, just like I like them!!! I also picked up a Mota Lita wooden steering wheel. In my opinion it really dresses up the interior!!!!! If the car is ever tracked the leather steering wheel can be reinstalled.
Thanks to everyone who provide input!!!!!! I have learned more about oil, lubrication, bearing clearances, gauges, viscosity, oil pumps, oil filters, than I ever thought possible!!!!!! If for some reason I remember to ask God when I see him as to what caused this fluctuation I will post here as he is the only one IMHO that would know!!!