How close, is to close for rad fans to water pump pulley space

Heating / Cooling / AC

  1. cudajames

    cudajames FABO Gold Member FABO Gold Member

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    Well, I am mocking up radiator and electric fans as I get ready to do the wiring,

    Car 66 barracuda with a 408
    22" Champion 3 row with dual 10" fans. Before mounting - I already know it will not fit (damn it).
    I reverse the fan shroud and use 1/4" spacers to allow some space between the shroud and radiator. The fans are a little recessed - so over 1/4" between fan blades and radiator. I am comfortable with this

    The fans do clear the water pump pulley, but just barely. See pictures

    Anything I should worry about?

    The 3 row is 2.5" thick and the 2 row is 1.75" thick - did I reach to far for the additional cooling

    thanks

    1.JPG

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  2. Ccas

    Ccas FABO Vendor FABO Vendor

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    You got a couple of issues going against you here. Normally that 3 row would do a better job but;
    1. You really need about 1" or more to create a decent suction affect with the shroud. In this case not only are you not getting any real vacuum effect.
    2. you are blocking the air flow from getting through the rad when you are at speed.
    3. dual 10" fans are VERY inefficient. In our tests, our dual 12" fans yielded 2800 cfm, our 16" fan 2500 cfm and dual 10" fans just 1400 cfm. Such a poor drop off in cfm that we abandoned the idea of 10" fans.

    I understand you needed the dual fans to gain some space. In your case, I would consider going back to the small 2 row and if a slim 16-18" fan will fit, then cross your fingers it's enough volume.
     
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    • MomsDuster

      MomsDuster FABO Gold Member FABO Gold Member

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      Could you shave some of the plastic off of the fan housing and install the shroud properly? I realize mine is a different application but that’s what I did to make mine work.

      C50ED7C1-D29A-468C-B9DE-0D7FDCCE56A4.jpeg
       
    • charles mill

      charles mill Wildman68 FABO Gold Member

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      make sure they are pulling air . advice at speed is mother nature. rad needs 2 b clean . fans of any kind will pull or push . but have a clean area to do either sounds he needs to sale . clean radiator is proof. your set up as seen is cool. do some tests . one fan or low coolant. but when u put back together and works as a bunch said on this site fm. and go.
       
    • Dana67Dart

      Dana67Dart Like a fine wine, only getting better with age! FABO Gold Member

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      Read this thread

      another 360/408 over heating

      Then ditch the shroud which is blocking almost 50% of the airflow through your rad, and put a stock fan on.
       
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      • cudajames

        cudajames FABO Gold Member FABO Gold Member

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        Yeah, I was reading that thread and noticed a lot of parallels between our cars and setup

        Seems like I have few alternatives
         
      • A408Cuda

        A408Cuda FABO Gold Member FABO Gold Member

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        You can see how close mine is in the overheating thread also. I think if it were to touch it would probably not cause to much damage but you would see some marks on your pulley and fans or shroud indicating where you need more room.
         
      • RustyRatRod

        RustyRatRod 30 Degrees Outta Whack FABO Gold Member

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        What kind of fans are those? If they move enough air (close to 4K CFM total) then you should be good. Lose the shroud and if the fans move close to or over 4K CFM you should be good to go.
         
      • Frnknsteen

        Frnknsteen FABO Gold Member FABO Gold Member

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        I dealt with the same issues on my Barracuda. I talked to Cold Case about it and was told the same thing as they said above.... The only thing that would fit was twin 10" fans and a tight shroud. They warned me that the twin 10" on a 22" radiator would mean that less than half of the radiator would be open to flow, and the fans wouldn't pull enough air. I decided to drop the idea of electric fans and go back to mechanical.

        I chose the same radiator you are using,.... mainly because all the Cold Case radiators had the overflow pointing to the driver side, and my overflow bottle could only fit on the passenger side.

        I ordered a Champion 3 row and a plastic shroud. It took a little bit of tweaking to get it to fit properly, but turned out good. I then went FlowKooler high volume water pump, Milodon high flow thermostat, and a Derale 8000RPM flex fan with a short spacer to center it up properly in the shroud. Everything seems to be working MUCH better now and it seems to stay cool now! Here's some pictures of what I originally had from previous owner, and what I ended up with.

        0918181651.jpg

        0918181650a.jpg

        1105181617b.jpg

        1105181617c.jpg
         
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        • cudajames

          cudajames FABO Gold Member FABO Gold Member

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          I will be using the flowkooler waterpump with the robert shaw thermostat

          The fans are Spal 30100435 - 800 cfm each

          The way I have it set up now will only not work and sounds like only compound cooling issue with the shroud so close to the rad, basically sealing the back of the rad. And in this scenario the fans might not be up to the task.
          If I install the shroud correctly, there would probably be over 1/2" of space between shroud and rad.

          Man, that didn't go as planned. I dig into some options.
           
          Last edited: May 21, 2019
        • straightlinespeed

          straightlinespeed Sometimes I pretend to be normal Staff Member FABO Gold Member

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          I had a very similar set up with 10" fans, but they drew a lot more air, I believe it was close to 1800cfm each.. I overheated because the shroud did not allow enough air to move through the radiator. I was going to cut more holes in the shroud but ended up going back to the factory fan, shorter clutch, and bought a factory shroud. Cools great now, not to mention the fans where noisy and never came off of high because it just couldnt move the air to cool it
           
        • jos51700

          jos51700 Well-Known Member

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          Part of the op issue is that plate with two holes, that's gotta go, as mentioned. You may as well cut that section of radiator out if you're going to do that.

          But I'm shocked that two ten inch fans don't have enough to cool at idle and slow speed. If you cut holes in your shroud, you're just allowing air to back flow when the fans kick on which renders fan and shroud worthless.

          Are you putting flaps on the holes in the shroud? All late models do this and it's a brilliant idea. Air flows through more of the shroud when under way, and the flaps seal shut forcing fans to draw through radiator when stopped.
          If the radiator can cool it when you're on the freeway with no shroud or fan, I'd think extra holes with flap and your fans would be enough, if I understand the problem at all (unlikely).
           
        • j par

          j par Well-hung Member

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          Remember in that 408 overheating thread the last post was him using a mechanical fan and it bending and going into his radiator. Would have that happened with an electric fan?
          I've got two 12-inch fans unshrouded and it seems to be working well but I believe my bigger radiator has quite a bit to do with that. I'd like it to cool a little better and I have some ideas for that as well. I will not go back to a mechanical fan. Don't like them never have.
           
        • cudajames

          cudajames FABO Gold Member FABO Gold Member

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          I haven't reached out to rod7515 yet since our whole install is similar - 66 dart and 66 cuda - same engine bay and everything is about 1/2" to big/long.

          What it is sounding like - I do not have a problem with wp pulley to fan clearance but with the shroud blocking cross flow through the radiator. Which has been compounded by me moving the shroud closer for fitment. I am tempted to cut out most of the shroud and reinforce where the fans attach - this would open up cross flow

          Oh, and possibly look for higher CFM fans
           
        • cudajames

          cudajames FABO Gold Member FABO Gold Member

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          How did you mount them?
           
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          • j par

            j par Well-hung Member

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            Kind of directly to the radiator..
            I use those push through zip ties with a little padding. I also got a bolt or two through the top and through the bottom.
            IMG_20190511_172653.jpg IMG_20190511_172633.jpg
            This is a cheap Summit radiator and I found that to have quite a bit more volume than my stock one did. I haven't tested it in the Dead Heat of summer yet but I was thinking of one of those Pusher fans or just trying to get a thinner singular fan upfront or back behind the radiator. I don't think I'm done yet but I'm nowhere near or even considering putting back on the whirling blade of death...
             
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            • Dana67Dart

              Dana67Dart Like a fine wine, only getting better with age! FABO Gold Member

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              Back in the day, (1980's) i mounted electric fans with the supplied zip ties like yours. worked for years BUT it did eventually eat through the tube from contact and vibration.


              On a side note:
              IMHO the biggest difference with factory shrouds and custom or home made is flow. Go get a box fan and see how much air moves with a piece of cardboard directly on the grill covering 1/2 of the fan, then move the cardboard 2 inch or more away from the grill.


              just get some flat stock and make some brackets that bolt to the factory radiator mount bolts and don't touch the Rad.

              the fans do not need to be significantly close to the rad, stock mechanical fans usually sit about an inch or so away, with or without a shroud they cool just fine.


              I have had both electric and mechanical and never had a problem with cooling and never had a shroud.

              Just My Opinion!
               
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              • famous bob

                famous bob mopar misfit

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                That thin shroud wouldn't work for me , tried it .
                 
              • Frnknsteen

                Frnknsteen FABO Gold Member FABO Gold Member

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                One thing people need to be aware of is the RPM rating of the mechanical fan. If you look close, a lot of the "Flex-Fans" out there are only rated for 4000 rpm. Mainly because a lot of them are either all aluminum, or steel frame with aluminum blades. I don't run my motor hard, but I knew I would exceed 4000 rpm fairly often just cruising around when I chose to get on it a bit.

                The one I chose was a Derale "Performance" fan. It's rated for 8000 RPM, and has a steel center frame and stainless steel fins. I think I got it from Mancini Racing if I remember correctly, but I could be mistaken. I ordered a lot of parts all at once when I redid my cooling system, so I don't remember for sure what came from where. Most came from either Mancini or Summit.
                 
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                • cudajames

                  cudajames FABO Gold Member FABO Gold Member

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                  Looking at the derale fans, I am seeing some rated at 10,000 rpm and they are between 15-18 inch fans

                  Could you post more details or a picture - cause there are literally 100s of options - so I could narrow the search. And read about flex and mounting distance.
                   
                • Frnknsteen

                  Frnknsteen FABO Gold Member FABO Gold Member

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                  Sure,... let me dig a bit, or look for my receipt to confirm where I got it. I'll reply back when I find it
                   
                • Frnknsteen

                  Frnknsteen FABO Gold Member FABO Gold Member

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                  Well,... That didn't take long. I bought it from Mancini Racing. You are right. The description now says "Rated up to 10,000 RPM". I don't remember where I got the 8000 RPM rating off the top of my head. Maybe it was 10,000 RPM all along and I was just remembering wrong, or maybe I was thinking of another model. Mine is the 18" Heavy Duty Flex Fan, Part# 17018

                  Here's a link:
                  Derale Performance Heavy-Duty Flex Fans
                   
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                  • furyus2

                    furyus2 Well-Known Member

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                    I have used that fan on several cars over the years. Works great. Make sure you don't buy the reverse flow fan like my neighbor did. I made a shroud to fit the aftermarket radiator, since the stock shroud wouldn't work. Shrouds not only help cooling at low speeds, they are a safety device. All my cars have them. Get the biggest fan that will fit the area without hitting anything.
                     
                  • Dana67Dart

                    Dana67Dart Like a fine wine, only getting better with age! FABO Gold Member

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                    IMHO...

                    Back in the day gas cost 20 cents per gallon and people didn't care too much about gas mileage. Fans were big, steep pitch and moved a tone of air

                    Than the gas crunch happened and gas cost twice as much almost over night. People and the government got concerned about gas milage. Fans were still large and steep pitched but to increase mileage a thermal clutch was added to reduce load on the eng at speeds where the fan is not needed.

                    Next, the pitch on the fans was reduced to put less drain on the engine but that resulted in less cooling. So a PROPPERLY DESIGNED shroud was added to help pull air through rad.

                    Finally engines got smaller V6, I4, radiators got larger, electric fans were added and all was right in the world.

                    The problem is we have big engines, small radiators, and we are trying to adapt the new tech with POORLY DESIGNED shrouds, electric fans etc.

                    The two are not totally compatable.
                    They can be made to work, but if you block 50% of your air flow with a shroud, your asking for trouble.

                    Before the flaming starts i recognise that shrouds have been in use for many years and with fans that do not have clutches and have steep pitches. Above is just a generalization.

                    My point is the need for shrouds etc was a result of trying to get beter fuel economy not to just improve cooling.

                    Let the flaming begin
                     
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                    • Frnknsteen

                      Frnknsteen FABO Gold Member FABO Gold Member

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                      There is definitely some truth to this. They help protect the fingers of people who aren't paying attention, or just aren't very bright! (Story to follow!!)

                      Back in the 80's when I bought my Charger, it had a 440 with a fan like the one shown below, with no shroud. I stopped by a friend's place once and we had the hood open and the car running. One of his friends that didn't know much about cars says "What's that blurry area (the spinning fan). We said "What are you talking about?", so he reaches to point at it and before we could stop him, he proceeds to stick his hand directly into the fan. Keep in mind that this is a running 440, a sharp/stiff fan, and no fan clutch. Luckily, he didn't lose any fingers, but cut them up pretty good.

                      In my opinion, shrouds do a very nice job of directing the draw of the fan to the radiator for better flow when you are stopped, but I couldn't agree more that they serve a safety purpose as well.

                      Fan.jpg
                       
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