What's better, the Hayden 2747 or 2797 fan clutch?

Heating, Cooling & AC

  1. Gerald Morris

    Gerald Morris Senior Member

    Messages:
    1,830
    Likes Received:
    511
    Joined:
    Mar 9, 2016
    Location:
    Tucson
    Greetings again Moparians!

    Now that I've got my shiny new Cold Case radiator, the NEXT item to upgrade is my fan. I bought and ran a Hayden 2707 last spring, but removed it just over a month ago and returned for the time being to my 6 blade straight steel fan to insure that plenty air is being pulled past that radiator.

    I've seen some anecdotes on the merits of the 2797 extreme duty clutch, and also some on the more modest and slim 2747 heavy duty model. Given how I had to shim BACK my fan just over 1/4 inch by using some extra nuts to insure it didn't eat the radiator even with the 2707, I have some doubts about installing the 2797. Can I make this work in my engine compartment or should I stick with the 2747? Do any of you owners of 1966 Chryslers in particular have experience with fitting too much fan clutch between the water pump and the radiator?
     
  2. cantflip

    cantflip Old Jagoff with a Hat FCBO Gold Member

    Messages:
    11,128
    Likes Received:
    6144
    Joined:
    Nov 1, 2015
    Location:
    Orlando, FL
    They give dimensions in their catalog, I know you have the skill set to fit one in there.

    eCatalog
     
    • Thanks! Thanks! x 1
  3. Gerald Morris

    Gerald Morris Senior Member

    Messages:
    1,830
    Likes Received:
    511
    Joined:
    Mar 9, 2016
    Location:
    Tucson
    Thx big big! T'was easy w the 2707. I reckon the amount of static friction for the temperature will be one thing to look at.....
     
    • Like Like x 1
  4. Gerald Morris

    Gerald Morris Senior Member

    Messages:
    1,830
    Likes Received:
    511
    Joined:
    Mar 9, 2016
    Location:
    Tucson
    After looking carefully at the characteristics of the "heavy-duty" vs "severe-duty" fan clutches, I've opted in favor of the 2747 (heavy-duty) since they have the same angular velocity (~80% of that of the water pump pulley) from the same static friction. The BIG difference between these is in the thermal characteristic of the clutch. The heavy duty clutch doesn't shed quite as much heat as the severe duty clutch does. This can be induced from the greater surface area of the severe duty impeller: the thicker vanes are to shed more heat, and this is exactly what Hayden intends.

    This being so, the issue of fitment then becomes paramount. Since the 2747 has a wider impeller, though not so thick, it lends itself to installing in front of a B block engine more readily than the 2797. The high pitch of my clutch fan blades will do nicely for pulling plenty air through the cooling system at this point, and I can use exactly the same arrangement I had for the 2707. Hayden makes it clear that both of these clutches are meant for high pitch blades, so I expect everything else being equal, the difference in heat shed by the impellers doesn't warrant the trouble of shimming in the thicker clutch. I hope future drivers will consider this matter with the same concern, and that I've done them some good here.
     
    • Like Like x 1
  5. cantflip

    cantflip Old Jagoff with a Hat FCBO Gold Member

    Messages:
    11,128
    Likes Received:
    6144
    Joined:
    Nov 1, 2015
    Location:
    Orlando, FL
    That's the one I was thinking of trying too. :thumbsup:
     
  6. Gerald Morris

    Gerald Morris Senior Member

    Messages:
    1,830
    Likes Received:
    511
    Joined:
    Mar 9, 2016
    Location:
    Tucson
    I'll let you know how it does when I get it on there. The pitch on my 7 blade 18" fan is great! Easy to understand why the 2707 isn't really enough to do it justice.
     
  7. ayilar

    ayilar Senior Member FCBO Gold Member

    Messages:
    4,382
    Likes Received:
    3955
    Joined:
    Jan 30, 2012
    Location:
    USA
  8. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

    Messages:
    15,050
    Likes Received:
    9503
    Joined:
    May 21, 2013
    Location:
    Marcellus, NY
    I use the 2747 in my car. I started using it on knowledgeable friend's advice. He said "It'll blow your hat off".

    It works better than the stock replacement (which was 6 months old) I had gotten from AutoZone.
     
    • Thanks! Thanks! x 1
  9. Gerald Morris

    Gerald Morris Senior Member

    Messages:
    1,830
    Likes Received:
    511
    Joined:
    Mar 9, 2016
    Location:
    Tucson
    I've been using the 2747 for 2 years now with an 18 inch DeRale 6 blade fan. It moves plenty air yet doesn't burden the engine so much as the old straight 18" fan it came with. Mark this caveat, at LOW rpm, you will probably want a good shroud and/or an electric pusher. My 66 Newport is a daily driver around Tucson, a misplaced border-burg with but one interstate around the west side, and a branch to Nogales south. Consequently, nigh ALL my driving is stop & go city, which in 115 F ambient temperature, requires EXCELLENT cooling!
     
    • Thanks! Thanks! x 1
  10. cantflip

    cantflip Old Jagoff with a Hat FCBO Gold Member

    Messages:
    11,128
    Likes Received:
    6144
    Joined:
    Nov 1, 2015
    Location:
    Orlando, FL
    Sorry I'm late... you should be happy with it, and it's pretty cheap...
     
    • Thanks! Thanks! x 1
  11. ayilar

    ayilar Senior Member FCBO Gold Member

    Messages:
    4,382
    Likes Received:
    3955
    Joined:
    Jan 30, 2012
    Location:
    USA
    Thank you! A Hayden 2747 is what I bought for Medina and also for Snow White, my '70 N-code Polara 'vert. Looks good, fits like a glove on Medina -- soon will be installed on Snow too. Will report on performance once I drive the cars.
     
    Last edited: Jun 3, 2020
  12. ayilar

    ayilar Senior Member FCBO Gold Member

    Messages:
    4,382
    Likes Received:
    3955
    Joined:
    Jan 30, 2012
    Location:
    USA
    Well, here is a performance update. @71Polara383 and I have installed a Hayden 2747 on three of our cars: Medina, my '71 T-code Monaco with the original 3443947 radiator; Elvira, his '70 Polara 'vert with a souped-up (U-code equivalent?) 440 and a brand-new Spectra CU332 radiator; and Snow White, my '70 Polara 'vert with a non-OEM radiator (which looks like a Spectra 332 and needs replacing).

    All three cars run hot -- Snow White all the time, so her radiator will be replaced; and Medina and Elvira only when driving for a few minutes in the passing lane (read at higher speeds) on Midwestern highways, mostly but not exclusively in hot weather.

    I do not think that the clutch is the issue in Medina's case, and I'll have her radiator rodded out by a specialist shop in the coming days. Elvira is more puzzling to both of us -- so as part of the troubleshooting Wyatt will be testing some other clutches he has around to see if the issue disappears. Will keep everyone posted.

    Meanwhile, if anyone has a suggestion for an alternative choice (as part of the "scientific experiment" we'll be running), I am all ears.
     
  13. Gerald Morris

    Gerald Morris Senior Member

    Messages:
    1,830
    Likes Received:
    511
    Joined:
    Mar 9, 2016
    Location:
    Tucson
    If you want to test a "clutch hypothesis," the best way to go about it is to obtain a DIRECT CONNECT 6 BLADE 18 INCH MOPAR FAN, bolt that on, and see what results. I have one of those, which came original to the 383 in my '66 Newport, and it managed to move enough air to cool the engine all through the summer of 2016 with the original 22 inch Hi Alt radiator Mopar equipped that car with.

    If a direct connect fan such as described above cools the motor on the highway, then you have an air flow issue. BUT:

    If the same symptoms persist, as I suspect they will, then look to the timing, radiator, cooling jacket et al. I just advanced my timing 2 or 3 degrees, which helped when running on the highway. We've been getting badly pounded by the sun this summer, which reminds me to thank the Lord for the inspiration to install that Cold Case radiator and the 16" electric pusher in front of the rest of the setup. One of these weekends, I mean to install an aluminum fan shroud to round out the air flow optimizations, though the car never had one previous. Many of its sort didn't.

    I also might try a 22" x 18" radiator, which are the dimensions of the original one, IFF I can find a modern aluminum radiator with 1.25" cooling tubes like the 22" x 16" I have. THAT would increase surface area and volume by 9/8, or 12.5% if you will. If I find a reasonably priced radiator mount for a 26", then I will go with that....

    Rodding out your current radiator looks like a reasonable plan for now. I also get somewhat better cooling by thinning the coolant mixture for summer.
     
    • Thanks! Thanks! x 1
  14. cantflip

    cantflip Old Jagoff with a Hat FCBO Gold Member

    Messages:
    11,128
    Likes Received:
    6144
    Joined:
    Nov 1, 2015
    Location:
    Orlando, FL
    Cheap fun... advance the timing a touch... see what happens.
     
    • Thanks! Thanks! x 1
    • Agree Agree x 1