Reply to "radiator cold engine hot - thermostat?"

When the internal recirc passage of the cleveland motor is functional, as it is with the edelbrock pump installed, you MUST use the proper thermostat.

What happens with the wrong thermostat, like the one you identify as the "PI" thermostat, is the motor is recirculating a large quantity of coolant full time, even when the motor is running hot.

This is most noticeable after a high speed run, like a cruise on an open highway or a freeway, then slowing down to stop & go traffic. Everything is fine while cruising on the highway or freeway at 60 mph or faster, but once the car slows down and enters stop & go type traffic it begins to boil over immediately.

cowboy from hell