Fixed fan to clutch fan

Steven Williams

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I have a 1973 Plymouth fury II with a 318 5.2 small block with a fixed fan. What kind of clutch fan would I use for a correct fit?
 
First thing is that you'll need a correct 7-blade fan. Then comes the fan cluteh to match.

The orig fan clutches had a solid mounting plate where the bolts held it to the water pump pulley, but it seems that all of the aftermarket replacements now have slots rather than 4 dedicated holes. The fan clutches were all "therrmostatic" with the flat-wound thermostatic spring on the front of them, which temperature modulated when the coupling locked-up more to cool a warm/hot engine. The main thing wouild be to get the correct length of the fan clutch's shaft for what you need for your 318 engine, to correctly positiion the fan in the fan shroud.

Seema like Hayden is one of the main brands of fan clutches these days. For reference, you might check on www.rockauto.com for correct part niumbers and shaft length dimensions. Might even find some replacement fan blades, too?

When Mopar Performance came out with their OEM-spec fan clutch/blade kit, that was the least expensive way to get a correct OEM-style fan clutch and new 7-blade fan. In more recent times, the price has escalated a lot and I'm not sure which fan blade is in the kit anymore, considering that all later-model vehicles have electric fans. But it might be worth a look. Might check one of the online Mopar Perf vendors for a price. Might also check with Van's, too.

Just some thoughts,
CBODY67
 
A clutch fan works best with a fan shroud.
If you can grab both from a car with air you should see a difference.
Even a 5 blade with clutch from any M body should work.
Hope this helps
 
Is the current radiator 22” or 26”? I have several used clutch fan assemblies and at least 1 fan without the clutch unit.
 
Factory spec, would be direct drive 5 blade for your car.

I would just upgrade to a fan shroud, and or a 7 blade direct drive. But if you want to have a "clutch fan", as they are known..........Torque drive or Thermal? There are two varieties.

Thermal with A/C and max cooling...Torque drive with HP applications non A/C etc.

Its really no use using a thermal in a non A/C application, although you can mount one.
 
I have a 1973 Plymouth fury II with a 318 5.2 small block with a fixed fan. What kind of clutch fan would I use for a correct fit?

For what advantage do you want a clutch fan? Cooling isn't necessarily any better, unless one gets a bigger surface area fan and a clutch which will engage when needed. The usual rationale is that a heavy direct drive fan steals plenty torque/power by turning at it's given rotational inertia all the time. If your engine NEEDS the fan fully engaged to cool, then a clutch fan will use just as much torque. The only savings I got from switching to a clutch fan from the 6 blade direct fan is on startup, when the engine is cold. I use a thermal clutch with an 18 inch 6 blade DeRale fan now. Once the engine has warmed up, during hot summer days, there is no advantage in a clutch fan, as even after sitting for hours after shutdown, the motor doesn't cool down greatly, so the dead intertia of the fan fully drags against the crank/belts as the 6 blade direct fan did.

WINTER mornings it helps to have a thermal clutch, or any other time after the engine has cooled back down. If you live in a COLD place, I'd say, get a thermal clutch fan for the dead start-ups.
 
It's a 26" radiator. Wanted to switch to a thermal clutch style. With A/C
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I have this one that’s 19.25” and ready to put into service for $50 + shipping.
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Not sure if that one will fit. The one on there now is 18". I will measure the shroud in a bit
I’ve got a couple of used 18” units with the clutch still attached for the same price. Clutches still feel good on them.
 
The fan on there now is a factory flex fan. My '77 Camaro 305 w/ac came with one of them. At first, I thought that was a neat deal, but later determined it was hindering things on the highway, effectively blocking air flow through the radiator at highway speeds. Went to an OEM clutch and matching OEM fan several years later and things worked better.

My issue was that even with a new Modine 3-core OEM replacement radiator, there was still a heat creep in the summer on the highway. Thought the OEM flex fan might be feathering out too soon, but a new OEM flex fan did not help. Neither did a new radiator. In my case, the 305 factory ac Camaros got the flex fan, but a 350 got the thermal fan clutch. Going to the fan clutch and OEM 7-blade fan cured that situation, years ago.

Just my experiences,
CBODY67
 
These are about 18.25”. The 2 are from ‘67 Imps and the odd one I have no idea.
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