Conventional metal band hose clamps have been around for nearly a hundred years in one form or another. They have a few inherit defects, one being they tend to become egg shaped if they are overtightened. They also tend to damage the radiator hose they are clamping when the clamp is over tightened. We have all watched car owners tighten a metal clamp until little pieces of rubber squeeze up between the slots on the metal hose clamp. That shortens the life of the radiator hose for obvious reasons.
Part of the reason for the coolant leaks in the winter months, is that rubber coolant hoses shrink in diameter when they get cold, while the clamping force from the metal clamp does not change. The result is a slight coolant leak that appears on the garage floor. Then the big tools come out and that clamp will get squeezed to within an inch of its life just like the radiator hose before it.
The fix is the new Gates Power Grip hose clamps. They are a heat shrink fit, and when it gets cold they shrink along with the radiator hose. As a result there is no leaks. You install them using a heat gun, the same one you use to heat shrink a wiring connection. The writing on the clamp turn color, from green to gray when they have had enough heat.
Gates Power Grip clamps will fit and seal any shape radiator neck, even one that is slightly out of round, which is quite common in antique vehicles that have been around for fifty plus years.
They come in all of the standard sizes for heater and radiator hoses, starting at 1/4" diameter and going all the way up to 3-1/8" in diameter. Once you have tried them for yourself you will decide to buy them by the box (10 to a box) which is the cheapest way to buy them anyway.
Here is a size chart that explains what size of Power Grip clamp you need for your application...