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Distributor vs Magneto

Discussion in 'The Hokey Ass Message Board' started by Voh, Dec 10, 2013.

  1. Voh
    Joined: Oct 18, 2006
    Posts: 854

    Voh
    Member

    Can someone explain to me the difference between a distributor and a magneto, or point me to some good writings about the two?

    VOH
     
  2. khead47
    Joined: Mar 29, 2010
    Posts: 1,728

    khead47
    ALLIANCE MEMBER

    A mag requires no external power.
     
  3. Voh
    Joined: Oct 18, 2006
    Posts: 854

    Voh
    Member

    Are they good for the street or more for the track?


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  4. hellrod666
    Joined: Sep 1, 2008
    Posts: 26

    hellrod666
    Member
    from seattle wa

    Mags were what most cars and bikes used. Cars like the model T and early bike like Indians. then they went to distributors. The mag makes its own power and in most cases it has a hotter more stable spark at as the rpm goes up. A dist. uses outside power and at high rpm the coil doesn't have time to charge so you have a weaker spark. That's where dual coil dist. comes in. So ya you can use a mag on the street. It needs to advance etc. And it will cost you alot more money. And if you break down you will have to order the parts to fix it. Your not going to find the parts at NAPA. Mags are cool and in some cases work really well. But for you money a dist. is a better deal. But if your like me you'll run what you like. So set what ever one you like up right and have fun.
     
  5. dan c
    Joined: Jan 30, 2012
    Posts: 2,171

    dan c
    Member

    and a magneto takes more power to run. like the man said, model ts had em 'cause you could crank-start it and a battery wasn't that important when most of the u.s. was rural.
     
  6. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 9,372

    Rusty O'Toole
    Member

    A magneto has a built in generator for power. It needs no external power source. They were very reliable when battery ignition systems weren't. They also make a hot spark at high speeds, not so good at slow speeds. Battery ignitions were the opposite.

    The modern coil ignition came in about 1915. After that magnetos were seen less and less on cars. They were still used on race cars, fire engines, and airplane engines.

    Since electronic ignition came in, they don't even use them on race cars. Modern electronic ignition is so good there is nothing to be gained from a mag.
     
  7. dreracecar
    Joined: Aug 27, 2009
    Posts: 3,078

    dreracecar
    Member
    from so-cal

    I beg to differ on the last statment, Racecars that rely on computers to function run electronic ignition and those that run Gasoline for fuel. Cars that dont have all that or run Alcohol or Nitro will run a Magneto or even 2 since all that required from them is to provide a spark. Some racers have tried to run EI on Alc but there was no measurable gain when one factors in reliability and the fact that batteries and altenators add more weight and complexity to the car then the 1-2 hp the mag absorbs at low speeds. Why the EI works better on gas is because gas burns as a vapor (FUEL burns as a liquid) and one needs a hot spark at a precise crank degree to make power. With a FUEL the firing point changes with heat-volume-compresion and the MAG offers a very wide spark duration that covers that window.
     
  8. I ran a mag in my 392 for about a year. Its fine for the most part but after fouling the plugs while stuck in traffic twice, I finally decided to run an electronic dizzy with a Pertronix. If it wasn't for getting stuck in traffic I would run the mag. It does look cool. It was expensive and expensive to get it curved for the street. Gotta pay to play.
     
  9. Mike VV
    Joined: Sep 28, 2010
    Posts: 2,134

    Mike VV
    Member
    from SoCal

    1. A Mag (magneto) does NOT have it's own generator. By definition, they are completely different (as is an alternator). A "mag" makes it's own power thru stationary perminant magnets within the housing. The spinning rotor creates an electric field...hence the power is produced and sent thru the wires on the rotor. The old points and condensors, rotor and normal cap is/was still used.

    2. As noted, ALL.....Top Fuel, Nitro Funny Cars, Alcohol Dragsters and Funny Cars run modern day "mags". Very powerfull 44amp mags.. two of'em...!!

    3. The older mags "of the day" didn't really make a ton of power. And because of the magnets of the day also being "old tech", they required remagnitizing fairly often.
    The older Vertex/Ronco/ScintillaSchiefer-Cirello/Don Zig (all related), Monster, Frankenstines, Harmon-Collins, et-al...did work better than the distributors of the day.
    Then came the CD ignitions (normal distributors used/use these also) and more powerfull longer lasting magnets (Alnico, ceramic, etc.). Then MSD combined the two and magneto power, history was changed.

    The early mags (Vertex etc.), the plug gap actually needed to "decreased" (.028" vs. .035") from the distributor gaps of .035" of the day. This is because of their relitivly low rpms, low power output. Then as the magnets got better/stronger and then the Capacitive Discharge (CD) came along, the power increase got huge, and plug gaps also got larger.

    For the street, yea, can be done. I wouldn't do it in a daily driver, but a weekend "period" hot rod...sure.
    Again, not much beats the multiple spark CD (NOT single spark as they once were) (MSD, Mallory, Crane, etc.) ignition of today.

    Mike
     

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