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07-17-2022, 10:04 AM
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#1 |
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Registered User
Join Date: Jul 2021
Location: Sylva, NC
Posts: 3
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Flex fan
I need advice on a replacement fan for my1969 C10. It has a 350 I have heard that the flex blade fans come apart. Is that the case?
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07-17-2022, 05:05 PM
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#2 |
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Registered User
Join Date: Feb 2013
Location: central California
Posts: 2,726
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Re: Flex fan
Yeah, many Youtube videos seem to agree. I like the biggest 6 blade clutch fan that fits the shroud and a Hayden 2747 clutch for a stout small block with an automatic.
Edit: most fans have a "replace after x amount of miles" warning label on the box. |
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07-17-2022, 11:35 PM
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#3 |
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Moderator
  
Join Date: Aug 2011
Location: China Spring, TX
Posts: 7,280
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Re: Flex fan
And they now make a 2947 fan clutch that is shorter.
__________________
Master Chief, US Navy, Retired 1964 C10 Step-side Short Bed - In Progress 2009 2500HD Duramax LTZ 1948 GMC Panel 1956 Big Window Stepside 1953 5 Window Chevy Stepside 1932 Coupe New Seat Foam for Bench Seats? |
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07-18-2022, 02:44 PM
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#4 |
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Registered User
Join Date: Dec 2012
Location: Temple City
Posts: 3,558
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Re: Flex fan
Flex fans don't do anything.
Electric fan or clutch fan are the way to go. |
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07-18-2022, 04:38 PM
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#5 |
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driving is in my blood
Join Date: Dec 1999
Location: Mesa AZ
Posts: 5,690
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Re: Flex fan
Had a flex fan on my 78 for the last 25yrs. Works fine. Doesn't explode.
__________________
-78 c10 short/step: 388cid, M20, 5/5 drop, lots more. Playtoy and first vehicle. -98 c1500 x-cab: 5.7L, 17" rims, 5/6 drop, flowmaster, helper bags,NBS rear disk brakes. -02 Suburban 4x4: leveled front -CBR600F4i, CBR600RR, CBR1000RR, and standup skis DISCLAIMER: I cant spell for the life of me. |
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07-18-2022, 06:30 PM
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#6 |
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Registered User
Join Date: Feb 2013
Location: central California
Posts: 2,726
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Re: Flex fan
This video is really good. https://drivemag.com/video/cooling-f...-masters-ep-20
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07-21-2022, 08:35 AM
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#7 |
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Registered User
Join Date: Mar 2015
Location: washington
Posts: 2,157
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Re: Flex fan
I am unsure if the flex fans design has changed but the typical flex fan has symmetrical blades. As in, all blades are spaced evenly.
This design will make you motor sound like a jet. Factory fans appear like they are missing a blade, this design is why they are quiet. It doesn't affect the balance because of how they are built. I notice more than a few factory fans on eBay. Consider using a clutch and factory fan. They just plain work and are quiet and according to the video use less HP. Thank Dave, for the link. The engine masters video was excellent but they didn't mention or measure the fan noise. Likely would have been impossible in the dyno room anyway. Cheers. Last edited by Accelo; 07-21-2022 at 09:18 AM. |
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07-22-2022, 12:43 AM
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#8 |
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Registered User
Join Date: Feb 2013
Location: central California
Posts: 2,726
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Re: Flex fan
My fan is one that is evenly spaced and I bought it new at O'Reilly's. I 've seen those odd spaced ones before and wondered what the deal was. Quiet is good, although I wouldn't say mine is loud really. When it comes to engine fans though I am leary of getting one with the potential of having a lot of miles on it in case it may be structurally compromised somehow. One thing I was able to do when I got a beefier radiator was to swap my heavy duty 2747 clutch for the standard duty one which did slow the fan a bit and helped the noise. The thing about a short pump 283 is that a single groove pully has a larger diameter than a double and when I had to go with a double, it spun the bleep outta the fan until I went with the standard clutch.
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07-22-2022, 09:44 AM
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#9 |
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Registered User
Join Date: Jul 2018
Location: Catskill Mountains,NY
Posts: 8,135
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Re: Flex fan
Worked great for 37 years . I just replaced the original that is stamped 1985 so it’s original to the truck . I kept it maybe it can be rebuilt ? This is a new Hayden unit
__________________
Mark 72 c20 custom camper Husky edition, 66 SS396 Chevelle 1964 Hawk, 63 Avanti,62 lark 1969 AMX , 1968 c20 stepside ,85 K20 1977 Suburban sold 68 anniversary. |
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07-27-2022, 04:11 PM
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#10 |
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driving is in my blood
Join Date: Dec 1999
Location: Mesa AZ
Posts: 5,690
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Re: Flex fan
Thats a clutch fan not a flex fan?
__________________
-78 c10 short/step: 388cid, M20, 5/5 drop, lots more. Playtoy and first vehicle. -98 c1500 x-cab: 5.7L, 17" rims, 5/6 drop, flowmaster, helper bags,NBS rear disk brakes. -02 Suburban 4x4: leveled front -CBR600F4i, CBR600RR, CBR1000RR, and standup skis DISCLAIMER: I cant spell for the life of me. |
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07-28-2022, 09:11 AM
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#11 | |
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Registered User
Join Date: Jul 2018
Location: Catskill Mountains,NY
Posts: 8,135
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Re: Flex fan
Quote:
__________________
Mark 72 c20 custom camper Husky edition, 66 SS396 Chevelle 1964 Hawk, 63 Avanti,62 lark 1969 AMX , 1968 c20 stepside ,85 K20 1977 Suburban sold 68 anniversary. |
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07-28-2022, 12:16 PM
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#12 |
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Senior Member
 
Join Date: Sep 2014
Location: Wenatchee, Wa
Posts: 897
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Re: Flex fan
My C20 came with a factory 7 blade clutch fan and all I did was replace the clutch unit and it works flawlessly. It is quiet and numerous 6000 rpm blasts and no issue.
The best choice imho. |
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