What do you think is better for cooling at low speeds, factory 5 blade fan with clutch, or solid flex fan 6 blade w no clutch. Car is 70 Duster 340 stock motor.
clutch fans only turn about 80% of crank speed,so move less air at slow speeds and
they are a ton of weight on the end of the water pump.
flex fans are avail. now rated to 10,000 rpm.
The pitch and number of blades also should be considered
Summit has hundreds..Derale,Flex a lite
and there are always older units at swap meets.
..think i'd go with a new one to be safe.
Mid seventies Mopars had nice factory units..try E bay.
I have the Summit G4918 flex fan.6 blades. Stainless steel. Works better than a clutch fan. Not noisy at all. I would definitely use a shroud. Makes a huge difference.