Reply to "Thermostat"

The 351-C, 351-M and 400-M engines all require a thermostat that has a copper nose or thimble attached to the base. This attachment protrudes into a matching hole in a brass disc (351-C) or in a casting (M-series) below the thermostat. The hole is a radiator bypass to promote fast warm-up. Using any thermostat without the protrusion will permanently allow up to about 25% of the cooling water to never pass thru the radiator and will result in overheating. The only exception is if you run certain aftermarket aluminum water pumps which do not have a matching passage, so the warm-up feature is disabled. Rear 351-C thermostats come in a limited number of temperature ranges, unfortunately. But testing has shown that in Panteras, the thermostat does not set the engine tempoerature- adding a 160 thermostat will NOT lower your engine temp, for instance.