Author	[Modern View]
Bobl1958 09-10-2012 13:09:02 68.98.205.31 Report to Moderator	Sure this is a dumb question, but my 620 has the ceramic resistor, which would make the coil have to be the coil WITHOUT the internal resistor? I assume the ceramic resistor is the resistor the coil is refering to? Thanks [Reply]   [No Email]
Bobl1958 09-11-2012 08:04:45 68.98.205.31 Report to Moderator	Re: 2 cyl ignition ? in reply to Bobl1958, 09-10-2012 13:09:02   The reason for the question is that I stopped in at my local CarQuest dealer that I get most of my parts and looked in the catalog for a coil. The parts book has one part number and the description is: 12v coil, and another part number and that description is 12v coil with external resistor. That is why it is so confusing. The parts book calls for both. [Reply]  [No Email]
John T 09-11-2012 09:45:04 216.249.82.117 Report to Moderator	Re: 2 cyl ignition ? in reply to Bobl1958, 09-11-2012 08:04:45   In the event the coil is for a 12 volt tractor that requires the external ballast resistor (which are in reality 6 volt coils) They usually are labeled something like "12 volts for use with external ballast resistor" or "12 volts requires external ballast resistor" However if they are full 12 volt rated coils (i.e. no ballast used), they may be labeled "12 volts" or "12 volts NOT for use with ballast" or "12 volts no ballast required" The above plus my post below hopefully helps you understand whats going on John T [Reply]  [No Email]
buickanddeere 09-10-2012 13:52:33 184.151.63.199 Report to Moderator	Re: 2 cyl ignition ? in reply to Bobl1958, 09-10-2012 13:09:02   1st and foremost . There is no &$;("&-)$;@(". thing as a coil with an internal resistor. If it's wired for bypass starting. There will be a 1.5 to 2 ohm resistor in series with the 1.5-2 ohm six volt coil primary. When starting, full battery voltage will be applied to the coil. A 12v coil is identical to a 6 V coil except there are twice as many primary windings. [Reply]  [No Email]
John T 09-10-2012 13:42:13 216.249.82.117 Report to Moderator	Re: 2 cyl ignition ? in reply to Bobl1958, 09-10-2012 13:09:02   Your coil is a 6 volt coil and youre correct IT HAS NO INTERNAL "RESISTOR". The external ceramic Ballast resistor drops 6 volts, leaving 6 for the 6 volt coil so all is well on a 12 volt system. Contrary to what many lay persons believe if you disect a coil THERES REALLY NO DISCRETE STAND ALONE RESISTOR TUCKED AWAY AND HIDDEN SOMEWHERE INSIDE THE CAN!!!!!!!!! A coil labeled "12 volts" or "12 volts no ballast required" is designed for use AT 12 VOLTS NOMINAL and will produce a spark at lowered voltage like 9 to 10 when starting if its real cold and still at 14.2 volts say when running with a good charging system.........While some call them "internally ballasted" again theres no discrete stand alone "resistor" hidden inside there. Its necessary 2.5 to 4 ohms (3 typical) of primary winding resistance is made up either of more turns of wire or higher resistance wire and NOT by adding an internal "resistor" to the primary winding coils...... A coil labeled 6 volts or 12 volts for use with an external ballast resistor (in reality a 6 volt coil) MEANS JUST WHAT IT SAYS. If its on a 12 volt tractor you need the ballast to drop 6 volts so the coil sees the 6 it was designed to handle and if on a 6 volt tractor the 6 volt coil (no ballast used) agian sees the 6 volts it was designed to handle Hope this helps John T [Reply]  [No Email]
M-MAN 09-10-2012 22:07:33 184.39.141.105 Report to Moderator	Re: 2 cyl ignition ? in reply to John T, 09-10-2012 13:42:13   John T; Since the external ballast resistor on a six volt coil is just turns of wire & that is added to the inside of a 12 volt coil how about we start calling them single and married to avoid any confusion? lol [Reply]  [No Email]
John T 09-11-2012 05:54:45 216.249.82.117 Report to Moderator	Re: 2 cyl ignition ? in reply to M-MAN, 09-10-2012 22:07:33   May as well lol, Ive explained this for years on here and its obviously NOT getting through. Maybe I should just start agreeing and "go with the flow" "Yeah theres a ballast resistor inside there" PS as Ive posted before yearssss ago in some 6 volt auto coils THERE WAS AN ACTUAL INTERNAL RESISTOR in a seperate compartment and the coils had a ring on the outside where the two seperate compartments were located, but Ive NEVER seen such a coil used on any tractors 30's through 60's etc John T [Reply]  [No Email]
Engineut2 09-10-2012 15:53:00 173.88.51.117 Report to Moderator	Re: 2 cyl ignition ? in reply to John T, 09-10-2012 13:42:13   Question...?? If you are using a "12V" Coil...is there as much Spark Voltage going to the Plugs when Cranking, as there is with a 6V Coil AND the Bypass circuit on the starter..giving a Voltage Boost (12V?)while Cranking..?? Seems there would be an advantage to using the 6V Coil, with the ByPass circuit... Clyde.. [Reply]  [No Email]
John T 09-10-2012 16:23:03 216.249.82.117 Report to Moderator	Re: 2 cyl ignition ? in reply to Engineut2, 09-10-2012 15:53:00   Youre right on point..... One reason for even using a 6 volt coil plus the external voltage dropping (12 to 6) ballast resistor on a 12 volt tractor is so you can have a short term higher energy spark ONLY WHILE CRANKING which greatly improves cold weather starting. When its cold battery efficiency drops,,,,,,the engine cranks much harder,,,,,battery voltage drops (maybe to 9 or 10) resulting in a weak spark when you need it most HOWEVER with an external ballast its possible to temporarily by pass it so full unballasted battery voltage is applied to the coil for a higher then normal energy spark while the starter motor is cranking. Once cranking stops coil voltage returns to normal so it dont overheat. Great question you had there John T [Reply]  [No Email]