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Ballast resistor bypass

Posted: Tue 3. Dec 2013, 09:57
by jrwertz

New to the forum. Just started restoration of a 59 Premiere this summer. Installed a new Pertronix II ignition system, coil, RF sheilded wires, etc. Instuctions indicate I should bypass the ballast resistor. I've tried both ways and it seems to make no difference whatsoever. Anyone else with this setup have any suggestions on which way to go? Just want to make sure I'm not causing trouble by eliminating the resistor, as it also has a wire connection to the starter relay in addition to the coil. Thanks!

Re: Ballast resistor bypass

Posted: Fri 20. Dec 2013, 10:17
by keithol
In 1955 and '56 US car makers went from six volt to twelve volt ignition systems. Most engineers improved the starting ability of these cars by using a bypass system. They did so by using a coil that would give ample ignition with the voltage reduced by a ballast resistor under run conditions. For starting,the solenoid was equipped with an internal contact that would be energized only when the starter was engaged . That is the reason there is a connection to the solenoid,that connection could be anywhere between the resistor and the ignition coil,the resistor was just a convenient place to connect. When the engine is running at anything above idle ,the system voltage should be around 14 volts. When cranking the voltage will drop to around 10 volts or less . The primary voltage of the coil remains more constant by having the bypass from the solenoid operate during startup. The main reason for keeping the voltage lower during operation was to prevent the contact points from burning. With electronic ignition systems that is not a problem Stock Ford electronic ignition systems do not use the bypass from the solenoid and run full voltage to the coil . The electronic systems , stock or otherwise may have voltage limiting built into them so if the manufacturer says its ok it should be ok . Otherwise ,trials I did fifty years ago bypassing the resistor using point type ignition resulted in a loss in performance ,either from arcing across the points or in the distributor cap.

Re: Ballast resistor bypass

Posted: Fri 20. Dec 2013, 16:42
by jrwertz
Thank you for the information! I saw the connection to the relay in the service manual schematic before, but did not know its purpose. Definitely appreciate the help.