I have a 56 Belair with a small block 327 in it. Runs hot when idling or slow speed. Original radiator with brass cowling on top. Can the radiator be cored or cleaned out? Is there a fluid that will help? How about a special oil?
If it’s the original radiator and if it’s plugged it can be rodded out at a radiator shop. Your radiator core is copper contruction and these radiators can have steel rods pushed thru cores to clean them out.
You can’t do that on todays aluminum radiators.
My memory is real hazy on this but I don’t think these cars came with radiator fan shrouds. A lack of shroud combined with a larger engine that the car never came from the factory with could cause overheating on an original radiator. Something to keep in mind if vatting the radiator out doesn’t cure it.
OK4450 is correct. The original engine for these cars was a 265 Cu In. The 283 didn’t appear until 1957. They did not come with shrouds. If you’re using the original fan and water pump, that may be part of the problem. It simply isn’t moving enough air/water when running. Investigate buying a new, flex bladed fan, and make sure the water pump pully is the correct size. If it’s too large, the pump won’t turn fast enought. If having the radiator core cleaned doesn’t do the trick, look at those options. Also, what temp thermostat are you using?
As the others have said, time to clean and upgrade the cooling system. A radiator shop can disassemble and rod out the core, they may be able to put in a better core with more/larger tubes. If that’s not possible, there’s lots of radiator options for your car. A high-efficiency fan (6 blades) will help. I had to do all this when I took my '72 Duster to Houston after adding aftermarket a/c.
Have the radiator serviced, install a shroud and a coolant recovery system from a later model vehicle…Or install the electric radiator fans from a FWD vehicle and control them with a dash-mounted switch…
@Caddyman makes a good point. I used electric fans years ago when driving a V8 Vega. A good friend of mine has a pair of electric fans installed on his V8 S-10 pickup so he can drive it in the summer months. Just flip the switch when the temperature gauge starts climbing and watch it drop back to normal.
I’d go with the electric fans, but I bet there’s a thermal switch you can plumb into the system, make it automatic.