The final piece of the cooling equation is air; without air circulation it is impossible to cool an engine. Even if you added a 55-gallon drum of coolant to the system, if you can’t remove the heat from the coolant, it is only a matter of time before the coolant reaches the boiling point. Your cooling system should include a high-quality radiator designed for the cubic inches engine and horsepower rating of the motor. Copper fins transfer heat faster than aluminum, but aluminum is lighter and the welded feature may be stronger. The choice is yours but a high-quality radiator of either material should do the job. Avoid using radiators from later model cars that have plastic tanks. The tanks do not transfer heat well and are generally a source of leaks with age.

There have been some interesting innovations in radiator design in recent years. Flex-a-lite has incorporated finned tanks on their radiators that vastly increase the cooling surfaces, but that’s not all. Inside the Flex-a-lite tank, fins are attached to the tank, effectively absorbing heat and transferring it to the tank surface. These innovative tanks have proven to give increased cooling capacity without increasing the size of the radiator.

Excessively painting a radiator will lower the efficiency of the unit and at least once a year use compressed air or a water hose to blow through the radiator from the engine side of the radiator. This reverse flow will dislodge all the debris that has collected in between the fins of the radiator, and you will be amazed at the amount of dirt, sand, bug carcasses, and other litter that comes out of the fin area.

So now that you have the coolant flowing through a clean engine and modern design radiator, what is the best way to provide airflow through the radiator? Early hot rods relied on a mechanical fan attached to the motor, and if you are building a very traditional hot rod that is the only appropriate fan. Hot rodders quickly moved from the conventional four-blade steel fan to lightweight stainless steel (and in some cases fiberglass) fans that are known as flex fans because the blades would cup a lot of air at low speed, then flatten out at higher rpm to minimize horsepower drain and air turbulence behind the radiator. These fans are still available and are far superior to factory fans.

Today most cars are cooled with an electric fan and shroud attached to the radiator. The shroud is all-important to ensure the cooler, outside air is being forced through the radiator. Electric fans from companies like Flex-a-lite or Cooling Components are remarkably thin and move a huge volume of air to ensure good cooling. Flex-a-lite offers both single and dual fan applications with built-in shrouds.

Now, there is just plain old heat dissipation from the engine block itself. On some high-end builds it has become fashionable to grind the entire block smooth, paint it with a high-quality primer, sand it, and then do a basecoat/clearcoat on the block for that supersmooth look. All that is fine, but bear in mind when you smooth a block you are reducing the surface area of that block significantly and all that casting texture you are grinding off the block is also surface area for heat dissipation. Likewise applying multiple coats of paint on a block is effectively insulating it from outside air contact. For those reasons I never grind a block smooth (and well, there is also the fact that this writer can’t imagine grinding on an engine block for a week) and good engine enamel is all that is required to cover the block. Should you be fortunate enough to have an all-aluminum motor, no paint is required and heat transfer from the block will far exceed that of a cast-iron motor.

Finally, providing a place for the hot air to exit is imperative for a good cooling system. Louvers in the inner fender panels or the hood itself will go a long way to exiting that heated air. The more air you can pass through the radiator and around the motor the more heat will be removed.

If you are experiencing overheating problems now is the time to look at upgrading one or more of your cooling systems, or at least give the system a full maintenance. In one afternoon you should be able to inspect and do a thorough maintenance on your cooling system. Check fan belt tensions, fan belt conditions, pulley alignment, all hoses and connections for signs of wear or leaks, and then clean all components inside and out. A day in the garage should provide you with a trouble-free cooling system for your next season of street rodding.