I've just rebuilt a small-block chevy engine (Chevrolet 350CI v8) for marine. It's been taken through the break-in with 5w30 oil, and now has 5w40 (mfg recommends 15w40, but I could not find that in a low detergent oil, I also run it in a colder than usual environment).
- Journal clearances were 0.003", or slightly under. Somewhat high but well within tolerance for the motor (2.2" journals).
- The engine does not consume oil, which makes me believe the piston rings are seated properly.
- The oil filter is a wix ph5 - I cannot find the spec on the relief valve pressure for this filter, but I can't imagine it would be as low as 40psi. The filter is new
With the 5w40 oil, the pressure at cold is ~40PSI at idle, and ups to the 60s with a bit of throttle. When hot, the pressure quickly climbs to 40psi under throttle (anything over 2000RPM), and stays there. All the way up to ~3800RPM which is where I stopped advancing throttle, the oil pressure barely climbs, if at all.
Is this possibly a sender issue? It shows the higher pressures when cold, but even then, not by much - the pressure gauge seems off by 5-10 psi, because it sits about that far below zero when off, and sits at 2-3psi (but bounces around slightly) at a warm idle.
I have not tried a mechanical gauge as I don't have one, but will probably be picking one up today.
The engine sounds happy. Oil is clean, apart from the initial greying at break-in, the new oil is in very good shape. I have yet (but plan to) cut the break-in filter open to look for shavings, but based on the condition of the oil, I am confident it is okay.