How to free up frozen AFB secondaries?

Fuel and Air Systems

  1. Moparnocar

    Moparnocar Well-Known Member

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    Got a AFB I'd like to use, decent shape, but secondaries are stuck. Been using pb blaster, no luck. Any old school tricks? Thinking heat next, but have to be careful of aluminum/rubber
     
  2. R413

    R413 Well-Known Member

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    What does it look like for corrosion damage and pitting?

    No heat here. Soak it in your favorite penetrant, for a long time, like 2 months. It really does work if it’s not to badly pitted.

    (Your favorite shouldn’t be WD-40)
     
    Last edited: Sep 18, 2019
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    • Lefty71

      Lefty71 FBBO Gold Member FBBO Gold Member

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      I'd soak it in transmission fluid, unless you have a way to prevent PB or Liquid Wrench from evaporating whilst soaking. Don't hurry it. HTH, Lefty71
       
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      • Dragon Slayer

        Dragon Slayer Well-Known Member

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        Disassemble it and you can try the soak in transmission fluid mixed with acetone. But it really does depend how abused it was. Do not put a wrench or pliers to the ends of the shaft. The steel is soft and will deform and twist, at which point the shaft is useless.

        Sometimes your lucky and it is minor corrosion and the shaft has not bonded to the aluminum and you can get some motion.

        But I have had other so bad, that to save the body, you have to cut the shaft out starting by slots at the blade hole to get sections of the shaft out through the venturi, followed by bending the blades to remove them. All while not damaging the bore of the carb. Really involved and you have to file any burs on shaft off to finish pressing out. So no damage to the body bores.

        I would inspect the shaft closer, is it heavily pitted, does venturi have pitting. If so, may want to move to different carb. If it is a numbers thing, at least it is the secondary shaft which is pretty common between AFB.

        I have even cut open the body of the carb that was no good anyway to see what and why it was bonded so bad and you would be surprised how corroded the steel gets along with swelling of the aluminum that lock the shaft to the body. It normally is on the inside (at the blades) where the body bore is necked down to fit shaft and prevent air leak that the shaft gets stuck. Good luck.
         
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        • Moparnocar

          Moparnocar Well-Known Member

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          Thanks for the info, looks like heat/pliers is not a good idea... Just wanted to use this carb cause I had it sitting around. I'll try soaking in acetone/TF othe than that, not worth the time to really tear apart, thanks for the help
           
        • dryheat

          dryheat FBBO Gold Member FBBO Gold Member

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          Try some Kroil (aka Miracle in a Can) ...
           
        • Cranky

          Cranky Banned Staff Member FBBO Gold Member

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          Can ya post a pic of it?
           
        • Dragon Slayer

          Dragon Slayer Well-Known Member

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          One AVS I cut out 180deg of the bottom of the body to show the shaft. Did it in all three spots. Left/Right and center. Still could not turn shaft by hand. Think about that if you think some magic solution can free one without damaging anything. Ultimately I had to remove about another 30 deg of body before the shaft would reluctanly turn and then finally pop out. If it is only a partial stick any of the penetrants will help loosen to turn.

          Now if your trying to save a shaft like a primary because the body is broken anyway, there are acid solutions you can stick the carb in overnight. It will soften the aluminum and ruin the body. But the shaft will turn by hand, be derusted and you can remove and salvage.

          I have a hemi holley base been sitting in ATF/Acetone for a month now still stuck, it's sister carb freed up after 2 weeks. I alternate spraying a penetrant and soak.
           
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          • old guys rule

            old guys rule Well-Known Member

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            WD-40 is Magic in a can can't go wrong
             
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            • 69L48Z27

              69L48Z27 FBBO Gold Member FBBO Gold Member

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              Why not try some EvapoRust and see if that helps. Penetrating lube doesn’t really dissolve rust does it? I’ve had stuff come apart from soaking in the EvapoRust before. Worth a shot if the oils don’t work.
               
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              • old guys rule

                old guys rule Well-Known Member

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                I agree. Just heard about it and ordered a can
                 
              • Moparnocar

                Moparnocar Well-Known Member

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                Good idea, might be my last resort
                 
              • Dragon Slayer

                Dragon Slayer Well-Known Member

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                Let us know how it works, but Evaporust only goes after iron oxide, won't do anything to the aluminum oxide that forms from the aluminum to steel contact.
                 
              • old guys rule

                old guys rule Well-Known Member

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                good catch
                 
              • retractable

                retractable FBBO Gold Member FBBO Gold Member

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                I have had good luck with hot engine oil and just letting the carb set in it for a week or more. I have never had to reheat the oil or have a carb shaft not loosen up doing it this way. The oil is too hot for my hand. I hope some way works for you.
                 
              • Moparnocar

                Moparnocar Well-Known Member

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                Interesting... How do you heat the oil? Stove top?
                 
              • retractable

                retractable FBBO Gold Member FBBO Gold Member

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                I like to use the oil drained from a combine or tractor when the oil is very hot. Stove works too just don't spill any.
                 
              • Dragon Slayer

                Dragon Slayer Well-Known Member

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                I did not try oil but did boil in water with detergent thinking heat would help and it did not work. Got old oil around, so will give that a try on the next one, but what does it do to the finish of cast aluminum?
                 
              • MoparLeo

                MoparLeo NRA PATRON LEVEL LIFE MEMBER FBBO Gold Member

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                If it was mine and important, I would send it out to be professionally rebuilt. They have the proper tools, chemicals AD experience to do it correctly. A sign that I posted in my shop said "Do what you do, Don't do what you don't do" Follow that advice and your life will be better for it.:thumbsup:
                 
              • Moparnocar

                Moparnocar Well-Known Member

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                Not important carb, just saving a buck. Just needs to lot drive . If I can't get it, I have a Holley for it, double pumper single feed, really odd carb
                 
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