Hot Rod Air
Most important is making sure the motor is positioned in the framerails so you can run a good-size fan. Keep in mind that the newer blocks are designed to run warmer temperatures than earlier motors (so don't be alarmed when you see 210 to 220 degrees
Southern Air
In a nutshell, you need a really good radiator fan, thermostat, and medium-volume water pump. Stock-size pulleys are your best bet, as GM and Ford have better engineers than any of the aftermarket sellers. I have an aluminum, dual-row radiator in my '46 woodie with 1.50 tubes and a 430hp Vortec 350. It will not overheat, but I also have one of our 16-inch, 225-watt fans with our adjustable thermostat.
Vintage Air
If an engine-cooling system has adequate components and is operating at its proper efficiency, no modifications should be necessary just because air conditioning is added to a vehicle. If an engine-driven fan is on the vehicle, we always recommend a shroud to maximize the efficiency of the fan. If a customer is using an electric fan as his primary cooling fan, we strongly recommend the addition of a trinary safety switch, which allows A/C system pressure to engage the fan in conjunction with and independent from engine temperature.
4. Do you recommend mechanical or electric fans with air conditioning?
Hot Rod Air
Engine-driven fans with a shroud will give you the most consistent cooling. Depending on the vehicle, if you can also run a pusher fan as a secondary fan, this will increase the air-conditioning performance at slow speeds. A second scenario is that anything less than a 17-inch engine-driven fan usually does not have the cfm to be used as a primary cooling fan; at that point, you should look at using a 14- to 16-inch electric fan and shroud combination. With air conditioning, you will need at least 2,500 cfm of airflow.
Southern Air
We highly recommend the six-blade Flex-a-lite stainless with our radiator shroud; however, this combination doesn't fit all cars, so get the best and biggest fan you can on the car. For instance, '33-34 Fords don't have much room between the water pump and the radiator, but one really good 12-inch fan and one 10-inch will fit on the grille side. If you're building a chassis, set it up with the motor back far enough to make room for a good fan.
Vintage Air
The key is airflow, and it doesn't matter if you achieve the airflow with an engine-driven fan or an electric fan. When using a mechanical fan, we like to see a minimum of a five- or six-blade fan with 2 inches of pitch. Be careful when selecting an electric fan as the primary cooling fan-many just don't have the capacity. We recommend selecting a fan with at least 2,600 cfm when the vehicle is equipped with air conditioning. Both fans will benefit from a good shroud and a smooth air path.
5. What interior modifications do you recommend when adding air conditioning (tinted windows, insulation, etc.)?
Hot Rod Air
Keep one thing in mind-air-conditioning systems do not make cold air; they remove the heat that is in the air, so you must seal all holes and door seals to keep the forced air from entering the interior. Insulate any surface in the interior, doors, firewall, headliner, upper cowl, kick panels, etc. If there is a surface, insulate it. This will also give you a quieter ride. Tinted windows, especially in the South and in warmer climates, will help-nothing more so than purchasing an evaporator large enough for your vehicle cab.
Southern Air
Tinted windows help, but nothing beats door seals and floor and door insulation. If the doors are not sealed, it creates a vacuum cleaner effect and out goes your cool air.
Vintage Air
The single most important factor in improving the efficiency of a climate-control system is how well the vehicle is sealed and insulated. You must keep the engine heat and outside heat load out of the interior of the vehicle. Tinted windows help reflect the heat soak from the sun, and this helps the air conditioner cool the vehicle more efficiently as well. Proper weatherstrip and door/ glass seals will also help isolate the interior and lessen the load on the A/C system. Be sure to seal any holes in the firewall, along with the clutch and brake pedals.