You can change out the fan clutch and nothing more and continue to run the current stock fan. It will be better if the smaller fan on the engine now is a seven blade unit. The new clutch is thicker but the location of the mounting flanges keep the fan the same distance front to rear.
My '67 cooling system was in good shape and was set up as delivered without AC. That meant it had the short 15.5" tall core, smaller 7" pulley on crank and larger 8" pulley on water pump along with the original H.O. 7 blade fan. It ran basically at thermostat all the time with no air. After I installed the Vintage Air unit the temps would creep up slightly while driving so I added the 2797 clutch and that solved the running problem but temps would still climb up to 190-195 if stuck in traffic on a 100+ degree day with the air conditioning blasting.. Next thing I did was change to the AC pulleys with an 8" on the crank and 7" on the water pump which went from an under driven pump and fan to an over driven setup. Still had the small fan but even with the AC on it never got over 190° in stop and go traffic. Went three summers with good results, but finally made the change to the deeper 17.5" AC radiator support and a Cold Case radiator along with going to the 19.5" fan and new shroud. Now it runs at thermostat regardless of how hot the day is or if I'm stuck in bumper to bumper traffic. Anyway, best to start with a new fan clutch and proceed from there if needed.
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Mick Batson
1967 original owner Tyro Blue/black top 4-speed HO GTO with all the original parts stored safely away -- 1965 2+2 survivor AC auto -- 1965 Catalina Safari Wagon in progress.
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