I have a '57 235 truck engine in my '47. Finally got the carb and coolant issues worked out and it runs like a top. Since I got the carb issues worked out and it idles smooth at 500 RPM, I noticed that the oil pressure is steady at just above 10 PSI after warming up. Is this low of pressure normal at idle? It goes up to 40ish at 2000 RPM.