Thanks for the info. The design of my original 48 Chevy 216 C.I. engine uses a non pressurized radiator cap. And yes when the temperature climbs towards 200 degrees plus I am losing coolant. I actually placed an overflow plastic reservoir on the firewall and it collects the coolant and when the radiator cools down the coolant returns to the radiator so I don't lose it anymore. I learned that trick from an owner of a 47 Chevy Panel Truck. My engine is still overheating. My radiator is an aftermarket OEM stock style radiator that is new, but it doesn't mean that it has maximum coolant flow through the core. I will tell you that the outlet temperature of my radiator is at least 20 degrees cooler than the inlet temperature.
