Because of their design-and specifically the slanted orientation of the radiator-Corvettes have always borne the unfortunate stigma of running warm or even overheating on hot days. While the angled radiator is not ideally designed for maximum cooling, like much of the Corvette it is a compromise between optimal performance and aerodynamic efficiency. In reality, engineers at GM spent considerable time designing the Vette's cooling system, and given the space constraints of the engine, they did a commendable job. Indeed, most Corvette engines will be adequately cooled with the stock cooling system. Add a hot engine or compromise the cooling system's design, however, and you're sure to notice your car's temperature gauge climbing toward the red end of the scale.
Keeping a Corvette cool generally isn't a problem so long as the engine is stock, and the factory cooling system components are in good working order. As our cars get older, however, radiators tend to get clogged with corrosion, fan shrouds and seals are damaged or discarded, water pumps lose their efficiency, and thermostats become inclined to stick. And if you've added an engine with more displacement or a higher compression ratio, the factory system may not be adequate at all. With these things in mind, the first step to ensuring your Corvette doesn't run hot is to evaluate the car's cooling-system components as well as its engine and intended use. Only then can you decide whether to restore the original system or make upgrades.
Although our C3 project vehicle was running when we got it, the car's cooling system was in obvious need of some help. While the radiator had been replaced with a factory-style re-cored unit, the fan shroud and engine-driven fan were missing, and two small aftermarket electric fans had been installed. Making matters worse, the radiator and shroud seals had deteriorated to the point of being nonexistent, allowing much of the cooling air to go around the radiator instead of through it. Since our engine is a fairly stock small-block, we decided to initially make the best of our factory components before upgrading to some trick cooling-system components from Zip Products.
Knowing we'd be modifying the existing engine-and eventually swapping to a higher-powered, larger-displacement unit-we decided to purchase the best cooling-system components possible in order to prevent an overheating problem. To that end, we called Zip Products and ordered the company's Direct Fit aluminum radiator with dual electric cooling fans. This setup is available for any Corvette and engine combination, and it bolts directly in place of the stock radiator. In addition to the new radiator, Zip sent a fresh thermostat, hoses, and water pump to ensure our engine stays cool even with the planned future upgrades. Additionally, we ordered a front spoiler to direct more cool air through the radiator. While we waited for our parts to arrive from Zip, we figured we'd service the car's current cooling system so we could do some driving.
Luckily, the radiator in our car was a fairly new piece, and since there weren't any obvious coolant leaks, we directed our attention to the electric fans that were installed by a previous owner. These fans were small, cheap aftermarket units and were barely held in place, so we decided to remove them along with their suspect wiring. Since the previous owner had provided the original fan shroud, we installed it with an engine-driven fan. This cooled our Stingray well enough for normal driving and commuting. Even so, the coolant temperature of our warmed-over 350 would still creep toward the warm side of the gauge while idling in traffic on hot days. Needless to say, we were happy when our new components arrived from Zip.