Ever been in traffic on a hot day in your classic and watched the gauge gradually move over 220 knowing it’s not going to stop unless you can get moving and get some air flowing?
Those old copper and brass radiators just weren’t made to handle it. The newer aluminum radiators do a much better job by using larger tubes.
Manufacturers such as Griffin make custom fit radiators for most vintage cars and trucks. If they don’t offer one for yours, a universal can be adapted or they will custom build one for you. Replacing the radiator is probably the most effective way for us to keep a car/truck cool.
Another way to get more air flowing and keep the heat down is by using electric fans. This is a must if you are switching to a late model motor. It also cleans things up by eliminating the fan shroud. They come in single or dual versions and you can either run a manual switch to control them, wire them so they are on whenever the engine is running, or put them on a thermostat to kick on at a certain temperature.
Radiator manufacturers usually offer fans or companies like Flex-A-Lite and Spal specialize in making fans.
Not an absolute necessity but high flow water pumps are available if you are really struggling to keep it cool.
This is one of the first places to check. Thermostats go bad and for the most part they are easy to replace. Its job is open once the coolant in the motor reaches a certain temperature, usually 180-195.
Once it opens, it lets the coolant flow from the engine to the radiator to get it cooled back down. When we do coolant system repairs, we always replace the thermostat.