Re: 6 volt to 12 volt

Posted by Bob on November 01, 2006 at 05:54:12 from (69.178.229.154):

In Reply to: Re: 6 volt to 12 volt posted by John T (Bob n Jim?) on November 01, 2006 at 05:19:22:

JohnT,

Using an ignition 'scope to observe the secondary waveform to the 'plugs will confirm that the spark polarity "flips" when the primary connections are swapped. (By convention, traditionally, ignition 'scopes tend to show the spark waveform upside down, to make it easy to observe, or visually measure, the peak firing voltage, which then goes "up", or more (positive) than the baseline, rather than "down", or more negative.)

My GUESS is that coils originally manufactured for (+) ground use have the secondary internally connected to the (+) primary terminal, while coils primarily intended for (-) ground use have the secondary internally connected to the (-) terminal. I would say the idea is to have the end of the secondary winding most directly connected to the condensor (when the points are open).

However, in actual use, it doesn't seem to make a noticeable difference in spark. After all, the primary resistance of only a few Ohms is the next thing to a dead short, compared to the 6000 to 7000 Ohms of resistance of the secondary winding that is, in effect, in series with the primary winding, when the breaker points are open.

Have you ever thought about the confusion caused when a coil marked "BATT" and "DIST" is swapped, from, say (+) ground to (-) ground? "BATT" becomes "DIST" and "DIST" becomes "BATT". Actually, marking the terminals (+) and (-) sure sounds like the best plan!

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