As mentioned previously I have not had much time to spend with the Spitfire this weekend. However, during the week I found time to install the new (non-thermostatic) oil cooler sandwich plate, new oil filter, and the 160 degree thermostat. Late this afternoon, After building oil pressure I started the engine and saw changes, some of which were expected, some of which were not.
It's colder today with a temperature around 50 degrees. When I started the cold engine, the oil pressure climbed slowly, not quickly like it had before. The pressure reached 50 PSI with the engine idling cold at 1000 RPM but would not jump above that when the throttle was blipped. I let the engine idle for about 20 to 30 minutes after which the pressure had dropped to about 42 PSI (same idle speed) and WOULD increase when the throttle was blipped... including going over the 50 PSI mark. I am confused by this. If the relief valve is opening properly, shouldn't the cold and hot upper oil pressure limit be (about) the same? If I was limited to 50 PSI with cold oil, why would the warmed oil be able to reach a higher pressure than cold oil? That's the part I don't understand.
What I was expecting was the increased oil pressure with the lower ambient temperature, colder thermostat, and a plumbed oil cooler. Hopefully I will receive the new relief valve parts this week and will find time to install them. However, the time change is going to make that awkward. Regardless, hopefully the weather will be good next weekend so I can take the car to run errands and see how the engine does under normal conditions, not idling.
Doug L.
--Previous Message--
: With cold oil I would expect it to be
: bumping the relief valve @ 2500-3000
: rpm, and drop as the oil gets to temp.
: