What is normal oil pressure for a 1992 Chevy 5.7L 350?

It depends on how your gauge is callibrated. It should be somewhere near the center of the gauge and shouldn't drop much when it's idling or hot. The manufacturer recommends a specific "weight" of oil, but when the engine gets older and worn the pressure will drop when hot and at an idle unless you select a higher viscosity oil. Oil lines have a pressure regulator which keeps the oil pressure from going too high. You should be able to see where the pressure is set when you first start the engine and everything is cold; the gauge should go up to that point and stop there consistently and should also stop there when you're running at highway speed. If the oil pressure drops much below that point when you're idling, the main and/or rod bearings are wearing which allows too much oil past.Again, IF the oil pressure is low, ahigher viscosity oil will staypressurized in the oil linesa little longer and will keep the engine from failing. If you have any questions, feel free to contact me directly.