Bill, thanks for the info in layman's terms. I know you can get a 12 volt coil that has printed on it "no external resister required" Can you tell us how that works if it starts on 12 volts and runs on 6 volts? On Sep 23, 6:45 pm, Bill Watson <chryco...@xxxxxxxxx> wrote: > Looking through the thread, could not see any explanation as to why > the ballast resistor. So, to explain what goes on - > > The ballast resistor has a piece of resistor wire surrounded by > porcelain. The ballast resistor cuts the voltage from 12 down to > around 6 volts. The voltage being "removed" is dissipated in the form > of heat. Porcelain is a good electrical insulator, and it is also a > good heat insulator. Thus the resistor wire breaks down after a few > years. > > The ignition switch has a START and a RUN (or ON) position and the > wires from each go to separate ends of the ballast resistor. There is > a second wire attached to ballast resistor along with the wire from > the START position that runs to the coil. Thus when you are starting > the car the flow of power bypasses the resistor and goes directly to > the coil. > > When you release the key and the ignition switch falls back to the RUN > position, power runs through the resistor. Thus, if the resistor is > dead, the engine will die the moment the ignition switch goes from > START to ON. > > The reason for the ballast resistor was cut the voltage back to 6 > volts with the adoption of 12 volt electrics as 12 volts wore out the > points too quickly. A few cars cars back then had the resistor between > the coil and the points. Then someone, a bean counter more than > likely, figured out it was cheaper to put it before the coil and then > you could use a lower power (ie cheaper) coil. One make actually went > back to a 6 volt coil when they moved the resistor. Which is why the > coil also became sensitive to the 12 volt current - it was no longer a > true 12 volt unit. > > Bill > Toronto, ON > > On Sun, Sep 23, 2012 at 4:15 PM, Douglas Sutherland > > > > <pluckedchick...@xxxxxxxxxxx> wrote: > > It was the ballast resistor! > > Looked at the back of my old one and it was worn through. > > > Thanks for your help! > > > $4.95 part to boot. > > > It's a sunny afternoon here in Seattle -- > > guess I'm going for a drive! > > > Thanks, > > Doug > > > -- > > -- > > -- > > Please address private email -- email of interest to only one person -- > > directly to that person. That is, email your parts/car transactions and > > negotiations, as well as other personal messages, only to the intended > > recipient. Do not just press "reply" and send your email to everyone using > > the general '62-'65 Clubhouse public email address. This practice will > > protect your privacy, reduce the total volume of mail and fine-tune the > > content signal to Mopar topic. Thanks! > > > 1962 to 1965 Mopar Clubhouse Discussion Guidelines: > >http://www.1962to1965mopar.ornocar.org/mletiq.htmland > >http://www.1962to1965mopar.ornocar.com/general_disclaimer.html. > > -- > > You received this message because you are subscribed to the Google Groups > > "The 1962 to 1965 Mopar Mail List Clubhouse" group. > >http://groups.google.com/group/1962to1965mopars?hl=en.- Hide quoted text - > > - Show quoted text - -- -- -- Please address private email -- email of interest to only one person -- directly to that person. That is, email your parts/car transactions and negotiations, as well as other personal messages, only to the intended recipient. Do not just press "reply" and send your email to everyone using the general '62-'65 Clubhouse public email address. This practice will protect your privacy, reduce the total volume of mail and fine-tune the content signal to Mopar topic. Thanks! 1962 to 1965 Mopar Clubhouse Discussion Guidelines: http://www.1962to1965mopar.ornocar.org/mletiq.html and http://www.1962to1965mopar.ornocar.com/general_disclaimer.html. -- You received this message because you are subscribed to the Google Groups "The 1962 to 1965 Mopar Mail List Clubhouse" group. http://groups.google.com/group/1962to1965mopars?hl=en.