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M starts and runs good-------but !!

B

Bob S.

Member
I know the same questions get asked every day of the week but I need to know for sure before rewiring. My 51 M was converted to 12V and tuned up before I bought it 2mo. ago, it starts and runs good but doesnt charge ( not a big deal right now because I still have 2 dozen things to fix on it before I start using it ) all I was going to do was put some wire ends on ( cant stand that twisted ends wiring ). I had copied a wiring diagram off this site a while back and thought I would double check my wiring, at first it all looked good but then I noticed the wires on the coil were oposite of the diagram . On mine the wire goes from ignition switch to -side of coil and +side to dist. Battery is neg ground. System has the ballast resistor and little bulb in line. Apreciate any advice ( about my wiring that is )
Thanks
Bob S.
 
With negative ground on the battery your wire to the distributor should be connected to the - terminal on the coil. Hal
 
On a negative ground system, the coil's (-) terminal goes to ground, as well, through the breaker points.

Your's is backwards, which makes for a slightly less effective spark at the spark plugs.

When the coil's polarity is correct, the leading edge of the spark at the plugs is negative-going. Since the center electrode is hotter than the ground electrode, this makes it easier for the spark to occur, due to the "Edison Effect". (Electrons are emitted better by a HOTTER object better than by a COLDER object.)

On modern vehicles with a "waste spark" system that fires 2 plugs at once, one fires with (-) polarity and the other of the pair fires with (+) polarity, yet the engine runs well 'cause the ignition system has a HOT enough spark to fire even the reversed-polarity plug efficiently.

On your old slow turning, low-compression tractor, the reversed-polarity coil will be a problem only if the spark is marginal to begin with.
 
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