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Thread: Auto spark plug wires

  1. #1

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    Question Auto spark plug wires

    Has anyone converted bendix mags to use auto spark plug wires??

  2. #2
    Mike Switzer's Avatar
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    I haven't had any reason to do it, but most of these mags were also used on tractors & they used a different cap that would take standard automotive style plug wires. A few years ago someone posted either a link or a pdf file (I can't remember which) on the AOPA board with a cross reference chart for both Bendix & Fairbanks Morse mag applications

  3. #3

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    Drew, why do you want to use the auto wires? Are they cheaper?

    I don't know anything about such a use of auto wire with a Bendix mag on a normal airplane, but I do know that a few Packard Merlins in race P-51s use an Autolite automotive spark plug which requires different automotive wires, still using the same type Rotax mag, I think, for all out at Reno.

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    Why? The aviation wires are better in every way.

  5. #5
    Mike Switzer's Avatar
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    Quote Originally Posted by turtle View Post
    Why? The aviation wires are better in every way.
    Some of the new automotive wires (especially the aftermarket stuff sold for racing) are pretty good - I don't know that they are better than the aviation wires though, I've never really looked into it.

    I'd be a little worried about the possibility of them coming loose though. Not like it is likely to happen, but you can't exactly pull an airplane over to fix a loose plug wire.

  6. #6

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    I am not saying I would do this but One of the advantages of building expermital is we can use products that are far more advanced than old technolgy.
    Set of spark plug wires from aircraft spruce about $180.00, spark plugs $21.50 x 8 =$172.00. Total $352.
    Auto spark plug adaptors appox $100.00, set auto wires appox $80.00, 8 auto plugs $5.00 x 8 = $40.00. Total $ 220.00.
    Was looking for ways to save money.
    And with proper maintance have never had a sparkplug wire come off any car i have owned and have flown for 7 years with a Subaru with auto plugs and wires and have never had one come off. Even if one did what are the chances of all 8 coming off at the same time.
    The problem is adapting the leads to the wire plate at the Maganeto.

  7. #7

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    Quote Originally Posted by dnew View Post
    Has anyone converted bendix mags to use auto spark plug wires??
    i haven't. i suspect it would be similar to the way shown here:

    http://www.g3ignition.com/slick harness.pdf

    dnew mentioned the cost of adapters to use auto plugs. you may choose to save a hundred bucks by using autolite 386 or champion d16 plugs. or other brand 18mm auto plugs of the appropriate heat range, reach, etc.. i use autolite 386. couple bucks apiece at advance or autozone, about six bucks if you buy a fourpack.

    your mileage may vary.

  8. #8
    Max Torque's Avatar
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    Converting the cap is fairly easy and straight forward.

    G3 Ignition has information and instructions on how to do the conversion. http://www.g3ignition.com/magmod.html and http://www.g3ignition.com/bendix harness.pdf

    You can purchase everything needed from G3i and do it yourself or they will do the caps for you.


    I have no worries about a plug wires coming off the plugs with a high-quality set of plug wires in good condition. (MSD 8.5mm Super Conductor Wires - about $90). Stick one of those wires on a plug and you'll see what I mean. I don't share the opinion that aviation wires are necessarily better than these in every way.

    There's a trail on the homebuiltairplanes website about spark plugs. There are certain brands of plugs you don't want to use. (I buy/use NGK AB-6 plugs - or AB-7 - depending upon operating conditions. Set gap at about .028"/0.7mm. AB-6 is "hotter" than AB-7.)

    Tom
    Last edited by Max Torque; 03-14-2012 at 01:45 PM.
    "You have to be alive to spend it..."

  9. #9

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    I've been using Autolite 386 plugs and automotive wires for 11 years with my electronic ignition. It kills me to replace the plugs every year. Six dollars down the drain. ;-)

  10. #10
    Max Torque's Avatar
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    Kyle,

    What engine are you using the Autolite 386 in?

    Unfortunately, I spend a lot more for the plugs in my experimental O-290 than you do - comes out to about $20 for all eight plugs...

    The Champion aircraft spark plugs I run in the engine in my Cessna cost about $26 each.
    Last edited by Max Torque; 03-14-2012 at 10:18 PM.
    "You have to be alive to spend it..."

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