Upgrading A C3 Corvette Cooling System - Cool It To Use It

Dewitt's Cooling System Makes All the Difference

Steve Dulcich Jun 19, 2007 0 Comment(s)
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05 To gain working clearance, the fan, belts, and radiator hoses were removed next. Don't attempt to remove the bulky fan shroud at this stage, no matter how much you wrestle, it won't come out yet without breaking it.

Corvette cooling experts at DeWitts have just the items to make all these problems fade to distant memories. DeWitts truly specializes in Corvette cooling components. Although the company sells correctly-detailed restoration cooling parts and radiators for pure OEM restorations, they are famous for their exceptionally capable Direct-Fit replacement aluminum radiators. These units are designed for maximum heat-rejection capacity, while configurations are available for Corvette applications to bolt-in exactly as a conventional OEM radiator. DeWitts pulls no punches and hides nothing when specifying the capacity of these radiators. Their ability to reject heat is given in the appropriate BTU numbers, instead of using vague and non-specific "horsepower" numbers that really give no indication of real cooling ability.

For our application, we ordered a DeWitts No. 73A radiator, which provides a 30-percent increase in cooling capacity compared to a factory radiator, and actually only weighs half as much. This radiator features superior aluminum construction, and has factory-type press-formed end tanks, a dual row-core, serpentine fins, and the factory-type upper-and-lower channels. The beauty of DeWitts Direct-Fit philosophy is the radiator will fit into the stock core support with the original brackets and isolators, and uses the original factory hoses. In an automatic transmission car, the cooling lines thread in perfectly, just like with the original radiator. Absolutely no modifications are required.

Although the DeWitts radiator will work with the original mechanical fan and shroud, we were more than eager to get rid of both, for good reason. The enormous and ungainly factory shroud makes it difficult to work at the front of the engine or suspension, and besides generally getting in the way while in place, it is a bear to remove. There is also nothing really attractive about the factory fan. Its removal promised less power drag, a cleaner, uncluttered look, and better access at the front of the engine. The solution, of course, is DeWitts electric fan setup.

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06 To continue with disassembly, the radiator core support needs to be unbolted. There are three bolts grabbing the sides of the support from the inner fender at each side, and two more at the bottom of the support.

We opted for the top-of-the-line Spal dual electric fan arrangement, complete with the Spal fan controller. While the stock factory fan moves air based on rpm, with some variability provided by the fan clutch, the programmable electric setup is based purely on temperature, and we can't think of anything more logical than that. With the dual fans and controller, the primary fan kicks in at the programmed threshold temperature and begins to run at 50-percent speed. The fan speed increases with temperature, as needed, if the temperature rises. At the programmed upper threshold temperature, the primary fan reaches 100-percent speed, and the secondary fan kicks in to help. As the temperature drops down, the secondary fan cycles off, and the primary slows as needed. All of this happens seamlessly, and the practical result is the temperature remains nearly constant, with more fan capacity jumping in only when needed. With the air-conditioning input wired, both fans will trigger to work at full capacity with the A/C on. Although the fans can be ordered separately and are very easy to mount, DeWitts will mount the fans to the radiator if ordered as an assembly.

So, the bottom line is what did this arrangement from DeWitts do for our Stingray? We got exactly what we hoped for-uncompromised cooling under all driving conditions. While this Vette was utterly unusable with the tired factory cooling system, it has now become our go-to daily driver. We installed a 160-degree thermostat and set the fans to start at 165, with the high threshold set at 190 degrees. The combination of DeWitts' high-capacity radiator and controlled fans keep the temperature virtually constant at about 180 degrees, whether screaming down the freeway at a constant 3,800 rpm or idling endlessly in traffic. In fact, the enormous heat rejection provided by the radiator results in the coolant seldom reaching the high threshold at 190 degrees to call into play the secondary fan.

The fact this cooling system transformed this Vette from a garage queen to a fully functional go-anywhere machine makes it the best modification we could have done, proving that capacity is king when it come to cooling.




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