David replied:

John; I have used one of these years ago on a race engine,the reason they were first used was to keep a constant speed for the water circulation. race motors at very high RPM were often circilating the water too quickly to cool it or the w/pumps were spinning fast enough to cause cavitation. The davies craig pumps are simple and effective but I would question the value of replacing the standard waterpump, what are you hoping to achieve?.......david