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Thread: Spark Plug Tire Inflator

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    Default Spark Plug Tire Inflator



    I hadn't heard of this before. My neighbor came over the other day and was telling me about wheeling his Willys when he was younger. It mentioned using a spark plug tire inflator. I looked at him like he was from a different planet. Within a few moments the theory became clear. The engine is essentially a big pump, so it can pump tires up too in an emergency! It requires an inflator setup with a check valve so the air doesn't escape while the valves are open on the particular cylinder being used.
         

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    Default Re: Spark Plug Tire Inflator



    That's pretty cool! I have a neighbor that was wheeling in the 1950's, he has some interesting stories about the old days lacking our technology.
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    Default Re: Spark Plug Tire Inflator



    The only downside is, your filling your tire compressed unburnt fuel...
    Could be very bad ju ju..
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    In a never ending search for the proper mix of dirt & rock !

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    Default Re: Spark Plug Tire Inflator



    But if you can unplug the injector you might be good!

    This is pretty interesting!

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    Default Re: Spark Plug Tire Inflator



    I had heard of doing that in the old days, but I didn't know if you should/could do it to a new vehicle.

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    Default Re: Spark Plug Tire Inflator



    Think it all be good to just get charged off the mountain. .
    Wouldn't want it long term
    ___________
    In a never ending search for the proper mix of dirt & rock !

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    Default Re: Spark Plug Tire Inflator



    This probably would have been in the 60's and 70's that he was wheeling. Unsure when they actually made these devices. Apparently he said that he made his own by modifying a spark plug (remove the ceramic and the center electrode) and then somehow attaching it to a hose. This was apparently before anyone had onboard compressors. He said that he had also converted his bumpers to be air tanks. The spark plug trick was a backup in case the bumper tank ran out of air.

    I had the same thoughts. Having a tire inflated with perfectly mixed fuel/air ratio isn't a fantastic idea long term but beats walking home! With newer vehicles you could unplug the connector to the injector for the specific cylinder you are using, which would reduce the amount of fuel pumped into the tire. Getting a 4 cylinder to run on 3 cylinders would be a stretch, but a 6 or 8 could easily do this.

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    Default Re: Spark Plug Tire Inflator



    I have also seen people use the vacuum system to unseat beads on tires.

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    Default Re: Spark Plug Tire Inflator



    As in attach a vacuum line to your valve stem and suck all the air out of it... Huh. Never thought of that! Youtube turned up a good video!

    https://www.youtube.com/watch?v=nZHMCQxALnU

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    Default Re: Spark Plug Tire Inflator



    Patrolman previously posted:
    "The engine is essentially a big pump, so it can pump tires up too in an emergency!"

    Except most air compressors don't have a 3-inch diameter piston. Actually cranking the engine without starting it may well be enough to air up a tire.

    This leads to a second thought, if you hold the gas pedal too the floor while you are cranking:
    A fuel injected vehicle will not cycle the injectors. My understanding is this a pretty universal default for clearing an injected engine that is flooded.
    A carbureted vehicle will not make enough vacuum to draw fuel through the idle or run circuits. All you get is the pump shot from pushing down the gas pedal. Disable the ignition and you are set to pump.
    ___________
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    Default Re: Spark Plug Tire Inflator



    Agreed about the volume of air being pumped by a piston.
    The amount of air would fill a lager tire quickly.
    No need to fully start the thing.

    I think a 4 banger will start fine, run worth a dam not so much.

    Nice trick if you have one built already.

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    Default Re: Spark Plug Tire Inflator



    Reviving and old thread here - but also identified something new here:


    A friend who picked up an old cj recently found one of these spark plug hoses in the tool box. I liked the idea but was not fond of putting fuel/air mix into the tires. Turns out (at least with this tool he found) that it does not flow the combustion chamber air into the tire. Instead, the cylinder pressure moves a piston/air pump in the housing that screws into the plug threads - that piston then pulls air from outside the engine into the housing through the slots and pushes it through the hose and into the tire. The trade off of course is that actual volume of air that the little piston can move is pretty small and it takes awhile to fill up a tire - but still a little faster than typical 12v portable compressor takes. If actual combustion gas was exhausted directly into the hose and tire then it would go a lot faster, but the air/fuel mix would go into the tire. Finally, I don't love the idea of running the engine with a non-firing cylinder for a couple minutes - at least with my old carb it would wash the cylinder down a and push a fair amount of unburnt fuel into the exhaust system. None the less - cool to learn how it actually worked.
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    Default Re: Spark Plug Tire Inflator



    MPFI folks could pull the power lead to the injector for the cylinder in use.

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    Default Re: Spark Plug Tire Inflator



    The only issue with the carbed guys is the air fuel mix.
    But it works in a pinch for sure.
    ___________
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    Default Re: Spark Plug Tire Inflator



    I was just thinking the same thing. Pull the fuse for the fuel pump, or disconnect the line for the fuel pump. Crank it over several times - just don't run the battery dead!

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