This is oil pressure at idle. It is at operating temp, and has been running 15 minutes, just drove down my street and back.
Good on you for getting a 'real' reading from a mechanical oil pressure gauge.
This removes a lot of variables, especially for those of us who don't get to
be next to the running engine.
IIRC, the classic oil pressure rule of thumb for the SBC was 10 lbs per 1000 rpm.
I would be interested in what your readings are using this gauge while
holding the engine at 2000 & 3000 rpm.
If you come back with 20 lbs & 30 lbs respectively, then with the
oil you are currently running your engine is still 'serviceable'.
By the way, 15W-40 oil in the colder weather and 20W-50 in the
summer may give you a few lbs of cushion and thereby give you less
stressed motoring.
And yes, a properly assembled new engine will give you 25-30+ lbs
at a hot idle, and hit the bypass of 55-60psi by 2500 rpm. But I've
seen in several places that 10 psi of oil pressure per 1000 rpm is
what you
need in order to operate properly. (And you did mention
that the engine is still quiet, both valvetrain and lack of rod knock?)
****
I know personally that even if I know the mechanical gauge gave me
'Go' readings, driving around with only the electric dash gauge showing
0 at a hot idle would still be a bit unnerving. If you are going to
continue to drive the truck as-is, I for one would either put your
test gauge inside the cab, or purchase a decent mechanical gauge
and install that in your field of view while driving. (See attached.)
For what it's worth --