Posted: Tue Jan 22, 2008 10:32 pm
Minor issue, but perhaps worth thinking about: Andrew pointed out one time in a discussion of internal IP pressure that the advance mechanism is activated by the difference between the inlet pressure and the internal pressure such that a supply pump will reduce that pressure differential, and, as a result, timing will be somewhat retarded. It's a minor issue because so many of these 20 year old pumps we use have never been re-calibrated and they're already retarded anyway, and in either case it can, no doubt, be compensated for by increasing internal pressure by the amount of pressure applied by the supply pump. (assuming someone takes the time to attach a pressure gauge and tach, and beat the little steel pin in the pressure regulator.)