My six volt V12 car has built-in dual ignition resistors that are not bypassed, even for starting. In some restorations of these cars, this has been added as an enhancement, though for me, in this case, it is not necessary in the least. I hot wired this car to start it when I first bought it, thus bypassing the resistors, and frying the coil. Once I finally figured out what I had done, I discovered that this coil is very special, and cost nearly $400.00 to replace. Though I assume that the resistors protect the points, they are also protecting the coil. I learn best from the mistakes I make, especially the expensive ones. Paul W. In an email dated 15/6/2005 5:17:48 pm GMT Daylight time, "Bill Watson" <wwatson5@xxxxxxxxx> writes: > >Actually, the original purpose of the ballast resistor was to protect the >points. ? Running 12 volts into the ignition system was found to wear out >the points fairly qucikly, so when auto manufacturers switched from 6 to 12 >volts they introduced a resistor. ? As the coil boosts the power to the >ignition system, the ballast was placed before the coil. ?Result, the coil >was actually a 6 volt unit and a number of makes continued to use the same 6 >volt coil on the 12 volt system. ? The resistor does protect the coil as >well, but only because it is basically 6 volt coil that had to be used as it >was placed after the resistor. > >>From the 1963 Plymouth-Valiant Service Manual : >"The ballast resistor is a fixed resistance in the ignition primary circuit. >During low speed operation, when the primary circuit current flow is high, >the ballast resistor temperature rises, increasing the resistance. ?This >reduces the current flow, thereby protecting ignition point life. ?At high >speed operation, when the primary current flow is low, the ballast >resistance cools off allowing more current flow, which is required for high >speed operation . ?During starter operation, the ballast resistor is >bypassed, allowing full battery voltage to the ignition primary cicuit." > >And which is why many electronic systems can use a 12-volt coil and no >resistor - no points to burn out. > >And I believe this rising and falling in ballast resistor temperature does >have some effect on the life of the resistor, especially as it is surrounded >by procelain. ?The ballast resistor on a 1965 Valiant I owned died and had >to be replaced. ?When I pulled the old one off the cowl, one end of the >resistor wire inside fell out - it had broken about half an inch from the >end. > >Bill >Vancouver, BC > > > >----- Original Message ----- >From: "Rob P" <fristpenny@xxxxxxxxxxx> >To: <mailing-list@xxxxxxxxxxxxxxxx> >Sent: Wednesday, June 15, 2005 7:10 AM >Subject: Re: IML: Ballast resistor > > >> The ballast resistor is to protect the coil. ?Some aftermarket coils don't >> require a resistor. ?This is probably the case with your MSD system. >> >> >From: "Klebert L. Hall" <swampyankee@xxxxxxx> >> >Reply-To: mailing-list@xxxxxxxxxxxxxxxx >> >To: <mailing-list@xxxxxxxxxxxxxxxx> >> >Subject: Re: IML: Ballast resistor >> >Date: Tue, 14 Jun 2005 22:25:04 -0400 >> > >> > >Subject: RE: IML: Ballast Resistor >> > > >> > >Dick the ballast master and fellow IMPers, >> > >Whet to start the 63 after 3 years of sitting. Found 3 bad lifters >before >> > >and replaced the lifters and push rods. I replaced the points with the >> > >electronic (the under the cap version). Car started right up and I was >> > >breaking the the lifters and the car sputters, dies , and no start. I >had >> >a >> > >buddy turn it over and had good spark. BUT, I look over and see the >> >ballast >> > >SMOKING! >> > >Looked around again and the newly rebuilt carb had a lake of gas on >each >> > >side. >> > >-Charles Major >> > >> > ? ?When my mechanics put an MSD in my '69, they took the ballast >resistor >> >out of the circuit... Maybe your system uses a different setup, though. >> > >> > ? ? ?-Kle. >> > ? ? ?'69 Crown 4DHT >> > >> > > > > >----------------- ?http://www.imperialclub.com ?----------------- >This message was sent to you by the Imperial Mailing List. Please >reply to mailing-list@xxxxxxxxxxxxxxxx and your response will be >shared with everyone. Private messages (and attachments) for the >Administrators should be sent to webmaster@xxxxxxxxxxxxxxxx >To UN-SUBSCRIBE, go to http://imperialclub.com/unsubscribe.htm > > ----------------- http://www.imperialclub.com ----------------- This message was sent to you by the Imperial Mailing List. Please reply to mailing-list@xxxxxxxxxxxxxxxx and your response will be shared with everyone. Private messages (and attachments) for the Administrators should be sent to webmaster@xxxxxxxxxxxxxxxx To UN-SUBSCRIBE, go to http://imperialclub.com/unsubscribe.htm