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Technical Any Issues with Shortening Fan Blades?

Discussion in 'The Hokey Ass Message Board' started by Crazy Steve, Apr 24, 2019.

  1. ZZ Top Chop
    Joined: Aug 12, 2018
    Posts: 163

    ZZ Top Chop

    What BJR said, seems easier just to buy a new shroud then to cut down a perfectly good fan. These are balenced for a reason and cutting could only make matters worse. Buy a shroud and you will never have to second guess if the fans gonna come apart or prematurely fail.
  2. Uhhh, you missed the part where I can't fit a wider shroud? Or find a smaller steel clutch fan?
  3. Selective attention???
  4. ZZ Top Chop
    Joined: Aug 12, 2018
    Posts: 163

    ZZ Top Chop

    Yes I did!o_O
  5. ZZ Top Chop
    Joined: Aug 12, 2018
    Posts: 163

    ZZ Top Chop

    I'd still leave the fan alone. See how it runs without the shroud this summer. From the comments, looks like people have luck cutting the blades down, I wouldn't be so lucky. Worse case scenario you could have a fan blade stuck in your hood or maybe your face, shoulder, etc. :rolleyes:
  6. I've been running it without a shroud for the last 4-5 years, and it wants to overheat in traffic/parade duty. I have to kick it into neutral and hold the revs up to bring the temp down every so often on really warm days. Mind you, this is in the temperate NW; if I lived somewhere where it actually got hot, it would be a serious issue. Part of the problem is I'm missing the factory shroud that covers the top front 4-5" of the radiator and directs air from the grill area, but because of the shoved-forward position of the radiator, even if I had it, it still wouldn't fit.

    This car was built in 'layers' in places. As I said, it's mostly home-built but the builder solved problems one at a time and didn't always take into consideration the next items that needed to be fitted. I'm sure that's how it ended up with this weird radiator set-up. Then when he installed the trans cooler, he routed the lines so the only way you can get the radiator out is by completely pulling the cooler, another item I'm fixing while it's apart. I've also got home-built alternator and PS pump brackets that I'm going to rebuild, more funky stuff.

    The fan is a symmetrical design (no odd blade spacing), so I'm not concerned with upsetting it's balance by trimming it. I believe that the shroud will improve airflow through the radiator more than enough to offset the smaller fan.
  7. Had the same problem in my Model A. Instead of cutting the fan, I drilled out the rivets, moved the blades inwards and welded them back to the hub. That way, I kept the fan's bent edges, which I guess have some significance (really don't know, but it must've been manufactured like that for a reason I guess).

    Worked fine, cooled the Cad 390 without problem (hood + hood sides), and was quiet and still balanced.

    gas pumper likes this.
  8. Behlings Circle Track Equipment in Butler WI, has a steel 15", 6 blade with 33 degree's pitch that moves a boatload of air. Problem is if you have your heart set on a clutch style, this is non clutch. Used these on many builds with great success and seeing these are for racing, RPM's won't be a worry. Part # 195-C17315 ( $29.99 ) if you would care to look. Good luck !
  9. japchris
    Joined: Apr 21, 2001
    Posts: 234

    from England

    I cut down my fan to clear the lower radiator hose in the way bangngears described -'Make the first cut , then use that as a template for the other blades. ' Didn't balance or weigh anything.
    Been driving with it like that since 2004.
    I thought it might wear the water pump bearings if it was even slightly out of balance, but I've had the same pump on there since then without any issues.
  10. Maybe I am the only one; but I don't think I have ever seen an automotive fan that has shown any signs of actually being balanced.
  11. wisdonm
    Joined: Jun 20, 2011
    Posts: 423


    I ran a cut down OE plastic fan for 15 trouble free years. Now I'm running a cut down OE steel fan, also trouble free for 25 years, so far.
  12. Atwater Mike
    Joined: May 31, 2002
    Posts: 9,504

    Atwater Mike

    Balance it as close as you can. Then check the balance with a down probe and timing light.
  13. bct
    Joined: Apr 4, 2005
    Posts: 2,976


    Could you weigh the scraps you cut off for piece of mind?
  14. primed34
    Joined: Feb 3, 2007
    Posts: 902


    Leave the shroud off and space the fan closer to the radiator?
  15. The fan is already about as close to the radiator as is possible; I could maybe gain another 1/2", but no more than that...
  16. 41rodderz
    Joined: Sep 27, 2010
    Posts: 2,429

    from Oregon

    I just want you to stay safe . Remember Napa doesn't sell body parts. Human that is.
  17. 41rodderz
    Joined: Sep 27, 2010
    Posts: 2,429

    from Oregon

    At least the ones in Oregon.:D
  18. Appreciate the thought, but truthfully I've been more concerned about that flex fan coming apart as I've seen those do that...
  19. 42˚18'N 83˚09'W
    Joined: Jul 29, 2008
    Posts: 127

    42˚18'N 83˚09'W

    Over the years I have had situations where I had to cut down fans fortunately without incident. The only thing I would add is IF you decide to cut the blades keep it as even as you can. Most importantly make sure your cuts are clean, deburred and as smooth as you can get them. As much as the blades will flex you don't want to leave any nicks or other inclusions on any surface for a crack or split to start. As far as balance, as thin as those blades are the weight difference is minimal again just keep them as close as you can. Best of luck...
  20. I'm trying to get away from those noisy flex fans....
  21. TWKundrat
    Joined: Apr 6, 2010
    Posts: 120


    I wouldn't hesitate to cut it. Just lay it out carefully and you'll be fine. Some people get skeered too easy and over complicate things (I'm plenty guilty of over complicating things myself from time to time).

    Now get to it! I want your next post to be showing us how it turned out.
    Blues4U likes this.

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