How does a clutch fan operate?

70orangeswinger said

Can I replace the non thermal clutch with a thermal clutch unit? I am still running the original fan.

Click to expand...

Yes You can.
Circa '78 replaced the 5 blade fan with a 7 blade & a ' thermal clutch' unit on Tinfish
(My '67 Barracuda forever project).
As to the 'no thermal spring flatface' Maybe--I stand to be corrected,--- as the first
j yard unit I bought (from a Diplomat Police small block unit) was dead & I tore it apart,
Low & behold, viscous fluid & thermal spring.

Apologies 70orangeswinger,
Back on topic :),
The new 'thermal clutch' I purchased moved the fan asy 3/8" closer to the radiator.
inclusive of the 'less aggressive' blade pitch on the 7 blade fan.
Bolt patterns were a non issue (fan to clutch, clutch to water pump).

If Your current setup has the same 'resistance' to rotation hot & cold,
The fan clutch is a door stop.

P.s, flex fans !!! bad ju-ju , unless You are going to examine same & replace
at regular maintenance intervals .