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Old 02-11-2018, 04:31 PM   #25
Brian T
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Join Date: May 2010
Location: San Diego,Ca
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Default Re: Replacement Ignition Coil

Originally Posted by 40 Deluxe View Post
Answer: It depends!......Depends on how much voltage is needed to jump the plug gap. If only 5,000 volts will fire the plug, that is all the coil will put out. Even if you have a double super whammy "40,000 volt" coil it will still only build up secondary voltage to the point where the spark is strong enough to jump the plug gap, which will never reach 40,000 volts on a Model A, or any stock engine (unless you have totally burned out plug electrodes or open wires, etc.). An ultra high compression or supercharged engine running at wide open throttle may need this much voltage capability, though.
To test coil output, try a "Lisle #20700 Spark Tester". Or, go to a shop with a scope, hook it up and pull a plug wire off and watch the screen.
Excellent post, this is the way I always remember it, using an oscilloscope can teach you much about the ignition system, spark plug cleaning machines had voltage testers built into them.
Nothing can be made foolproof, ---- fools are ingenious bastards.
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