Thread: Aluminum vs Brass Radiator

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I have a 46 Ford coupe that is very similar to your 40 Chevy. When I bought the unfinished car, it came with a massive 4 core copper/brass radiator. Due to the engine being mounted a little too far forward, there was not much room for a large fan. The car ran hot from day one. The 383 stroker didn't help. It would run 190-200 on the highway and spike to 230+ before you could get off the road and to the pump at a gas stop. This constant overheating finally cooked the 383 and I had to replace it with a 350. I tried every fan and shroud combo I could fit (mechanical and electric) and nothing helped. I refused to believe the radiator was at fault, but finally decided to change it since that was the only option left.

I swapped it for the largest aluminum Griffin Rat Rod series radiator I could get in. Has two 1 1/4" tubes. I also fitted a Cooling Components electric fan and shroud. This combo just barely fits. Fan has a super powerful motor that requires a 60+ amp relay if ran in single speed mode. The car finally runs decent temps. 180-185 on the highway with AC and 200 in traffic on a hot day. Still can't run the AC in traffic though.

As I understand it, copper does conduct heat better than aluminum, but copper/brass radiators have to be soldered together with lead solder. The fins are soldered to the tubes during construction and the lead interface between them acts like an insulator. Aluminum radiators use various aluminum bonding processes to attach the fins to the tubes, so there is a more efficient heat path. Also, aluminum allows for larger tubes so there is effectively more water in contact with the tube wall.

I do have to add that much of my problem is airflow related. With the engine too far forward, air has much harder time making it through the engine compartment. I have plans to correct this in the near future, as well as fit a larger cored radiator.