I am another one in the no flex fans club - I race in SCCA events and they are not permitted for a darn good reason. And I have had them let go, with one in particular creating a nice hole in the hood of a classic 1969 Ford LTD. A fan with a clutch will be as effective in cooling, if not more so, and is much safer. Check the clutch! Other items to check that caused some heat problems with my C3:
1. Shroud in good shape and properly installed
2. seals between hood and radiator are critical to prevent air from just spilling over the top of the radiator
3. air dam/spoiler in place.
4. if all else fails, get a nice Spal electric fan to supplement the cooling
Just my humble opinion....good luck. I had to work on mine to get it cool during NC summers.
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C3: 1979 Corvette Coupe, Auto, L-48, Red/Doeskin (my wife's fave);
C4s: 1986 C4 coupe (SCCA road race car), satin black, 4+3, Z51 package, L-98; & 1993 C4 coupe, white, 6-speed, LT-1.