Clutch fan?

[7tonemonte]

Going over some stuff on my car for the new season and I was curious about clutch fans.  
 My car is a 71, small block (mostly stock) when I got it, it had a basic 4 blade fan on it, no clutch setup.  
last year at Carlisle was the first time it ran hot ever on me, and since then I flushed the coolant and refilled, it had been probably 10 years since I did it. 
  Question is, did they all come with a clutch fan assembly and what,if anything, would be the benefit of putting one on my car? Also, any special one?  
no interest in electric fans at this time

Thanks!    Looking forward to driving it again here, waiting for nicer weather 😁

[DragCat]

Just saying, if you left the show grounds through the construction area you weren't alone. A few members had high temp issues. I know it doesn't answer your question just fyi. 

[7tonemonte]

7 minutes ago, DragCat said:

Just saying, if you left the show grounds through the construction area you weren't alone. A few members had high temp issues. I know it doesn't answer your question just fyi. 

Yea Mark, that’s exactly where it happened.   I’ve been caught up in plenty of hot weather but that’s the first it hit 220ish.  
 

[jft69z]

Does the car have A/C Tony?

[7tonemonte]

19 minutes ago, jft69z said:

Does the car have A/C Tony?

No A/C Joe. 

[Dtret]

2 hours ago, 7tonemonte said:

Yea Mark, that’s exactly where it happened.   I’ve been caught up in plenty of hot weather but that’s the first it hit 220ish.  
 

That weekend was pretty excessive. I overheated too ( and I’m not talking about my cars lol. 😝). 

[cbolt]

Correct me if I am wrong, but I believe a clutch fan will disengage when either the water pump shaft reaches a certain rpm, or in the case of a thermostatically controlled clutch fan, when the temp is down sufficiently to no longer need air flow. 

Your mechanical fan will draw air all the time, regardless of engine speed or temp, varying only by the speed of the water pump shaft. At idle, the fan only spins so fast on both the mechanical and clutch fan, so an "upgrade" to a clutch fan would not aid in cooling while idling or driving slowly in traffic.

I believe the desired effect of a clutch fan was to improve fuel economy by not dragging the horsepower down driving a fan that isn't needed at highway speeds. 

Your best bet is to keep the cooling system clean by flushing it every season and replacing the coolant. 

My car has a clutch fan and an electrical fan to help keep it cool. It gets pretty steamy down here in FL, so fighting overheating is always a top priority. 

[John S]

I upgraded my radiator to a three row radiator. Now, I have the small radiator with the three bolt top cover and a 180° thermostat. I also put a seven blade GM fan with a centrifugal clutch fan on. I have no problems and it does get hot down here in Georgia south of Atlanta. Temperature will run around 200° if I am in heavy traffic for an extended period of time otherwise between 180° and 190°.

John S

[DragCat]

That's why I upgraded to electric fans in both my rides. Yea, doesn't help you stock original guys 🤣 

[420ponies]

Hi Tony! Glad to see you back on here. Have a 7 blade "flex" fan on mine ,3 core radiator, 160 degree thermostat (with 1/16" hole drilled for airlock in system). Never had problem with overheating (most 210 in Carlisle),usually no more than 180-190 in the summer. The flex fan draws air more on the lower rpm's.Had this on sine on the road, with no issues. Now, if you're going for a clutch style fan, a '77 corvette style would be the preferred  one for your set -up. 7 blade (wider blade),with clutch (tighter on start-up and flows air very well. I see Jeg's has the 18" fan ($97.00?) .Fan clutch is for heavy duty from Rockauto. Hope this helps in your decision. That fan will have very little clearance (good), may have to adjust your shroud.

Edited April 15 by 420ponies
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[7tonemonte]

So what was stock on these cars?  18”, or 17”?

[Scott S.]

Like James, I went with the 18" aluminum flex fan, 160 degree thermostat (with the hole) and the only time I get over 180 degrees is on a hot day in traffic. 

Prior to the changes, I'd hit 220 degrees in traffic on a regular basis. And I'm running a fairly stock 350 with no A/C as well. 

[420ponies]

5 hours ago, 7tonemonte said:

So what was stock on these cars?  18”, or 17”?

I think they were 17" when stock? I went with something that fills the shroud (and 18" does). If you want the "clutch" ,then that corvette would break the ticket. If you want "constant" airflow at lower rpm's, then the flex fan would do it for sure. Make sure you get the wide blade style flex fan.