Oil pressure question...I promise it's not another "who likes what' thread!

beanhead said
Just got my 440/505" on the road. Broke the cam in with Comp 15w-50, changed oil & filter after cam run-in, refilled with the same grade oil, and put a few hundred miles on it. I wanted to get some new oil in it, so I went one step thinner and dumped in some 10w-40. Hot pressures with the 15w-50 were 25-30 psi at idle and up around 60 after about 2500 RPM. Now, with the 10-40 I'm making 20 psi max at idle and 55 thereafter. Seems a little lower than I'd like to see on the gauge, but the engine 'seems' happier. A little quieter up front and smoother, and the gauge needle is much steadier. Bigger difference appears to be at idle--I'm at 950-1000/neutral and 850 in gear (auto trans). By the way, it be hot here...
It's in your basic fun street car, lots of zipping around town miles and sitting in traffic. Famoso T&T night eeevery once in awhile. Main feed passages were enlarged to 9/32". Mains came in at .003" rods are .028". Clevite 'H'-series bearings from the 440source kit. EDM lifters on a solid cam, 250 @ .050" with .555" lift, not super crazy. Running a high-volume pump. Mancini/Harland rocker arms (no bearings on the shafts) and a B3 kit on the top end, plenty of oil up top every time I've pulled the covers. All of these factors together seem to be contributing to the pressure readings, which is fine, "it is what it is"..
So, okay to run with the 10-40? Or go back to the heavier stuff?
Thanks

Rule of thumb is that you want 10 p.s.i. for every 1,000 rpm turned..Example..7,000 rpm you want at least 70 p.s.i...A good high volume pump along with proper bearing clearance should be higher than what your oil pressure is showing..If you're tolerances are correct you can try pulling the spring out of the oil pump and extending it a little..In every build I've ever done with a high volume pump my oil pressures have always been at 70 or a bit higher above idle..As far as oil goes I use Kendall..You can add a little zinc additive to it just for good measure..And I highly recommend not using Fram filters..Ive turned them upside down and hit the bottom of the filter and have had metal shavings fall out on many occasions..If you want a damn good filter I recommend the #51515R Wix racing filter..Ive cut both the Wix and Fram filters open and Wix is a much better filter..