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Old 04-14-2017, 04:08 PM   #2
JSeery
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Join Date: Nov 2012
Location: Wichita KS
Posts: 16,132
Default Re: coil positive ground

Need to keep the polarity straight. A coil will run connected backwards, but not correctly (as designed). In your case the (+) terminal should be ground (connect to the distributor and the (-) terminal should be power (connect to the battery through the ballast resistor and ignition switch).

"There is a way to check directly which way the current is flowing in the high tension circuit. Disconnect a spark wire from a spark plug (or the coil wire from the distributor cap). Hold this HT wire near a grounding point (or near the connector end of a spark plug), and position the tip of a graphite pencil in between. When you crank the engine (no need to start or run) you can observe the resulting spark jump between wire and pencil, and between pencil and ground (or spark plug). A flare (hard to see) toward the plug (or ground) shows correct polarity while a flare toward the coil shows reversed polarity. If the flare goes toward the coil, just switch the primary wires on the coil and make note of the connections for future reference."

"Can't see the flare? Not sure yet? You can also check spark polarity using an analog (moving needle) volt meter. Hook up a voltmeter with the negative lead to the plug terminal and the positive lead to the block. Set the meter on the highest volt range. Crank the engine over (no need to start it), and you should see an upward swing of the voltmeter needle (don't be concerned with taking a reading). If the needle swings down off the scale, your coil is hooked up wrong. To correct it reverse coil primary leads. Do not worry about the coil markings, but make note of them for future reference."
Attached Images
File Type: gif spark_polarity.gif (12.5 KB, 46 views)
File Type: gif spark_polarity2.gif (4.6 KB, 37 views)

Last edited by JSeery; 04-14-2017 at 04:54 PM.
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