Tom, the main difference between a mag [magneto] & a distributor is that a mag is self contained & DOESN'T need a battery to produce a spark. A distributor needs an external battery or power source to operate. ~Mags were used on many of the hand start tractors because many of those tractors didn't have batteries or electrical systems. ~There are many types of both mags & distributors. Most mags use an internal ignition coil that is both mounted & powered internally. Most [but not all] distributors use an externally mounted ignition coil. ~To get a little more technical, most [but not all] mags have fixed running timing [usually in the 20� to 30� range with some type of retard mechanism to reduce the spark advance to around 0� for starting purposes at cranking speeds [usually under 300 RPM's]...Most distributors have a variable spark advance that slowly increases the spark advance as the engine RPM increases [that's it's big benefit]. ~Most magnetos also have some type of low speed impulse [a type of hold & let go mechanism] that not only retards the spark at starting speeds but also momentarily holds the rotating internal generator with a spring then lets it go as the impulse TRIPS. That not only retards the spark for starting but also increases the internal generator's speed to produce a hefty spark at low initial cranking speeds, as the mag's RPM increases that impulse quits holding & letting go & the speed of the mag's internal rotor [generator] is then fast enough to run the mag without the impulse tripping. ~Magnetos have been around for years & if kept in good repair will run a tractor within it's designed operating range with plenty of power & reliability. A distributor's main advantage is the fact it has a built in spark advance & is easier to service & understand for most people. ~Most distributors produce a slightly stronger spark but some of the more popular mags can also be built to produce a very strong spark. ~Another way to look at a magneto is it is just a distributor with a generator built into it so it can make it's own power, it still has a coil [just like a distributor], it still has a set of points & condenser [just like a distributor], it still has spark rotor & distributor cap [just like a distributor]..... .. ~Any more technical questions just post back or E-Mail [email protected]
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