Posted by Vaughn [172.68.142.68] on Thursday, April 27, 2017 at 23:13:21 :
In Reply to: Ignition Ballast Resistor Question posted by Greg Coffin [172.68.34.103] on Thursday, April 27, 2017 at 12:41:12 :
But what the video doesn't provide is the theory behind it so you understand it's operation. Forcing more current through the primary windings of a coil will result in more secondary voltage being produced when the points open. The way you get current through the coil windings is to increase the electrical pressure or voltage. As the video demonstrated, placing a resistor in the circuit reduces the electrical pressure and that cuts the amount of current going through the coil windings. So what's the effect?
1. You have less current to generate high voltage to the plugs during cold starts when fuel ratio is higher and you need it the most. Fuel/air are resistance that requires more electrical pressure to generate a spark the will jump the electrode/side electrode gap.
2. When the engine is running, the electrical pressure drops to 9-volts extending the life of the coil and points.
3. As RPMs increase, the resister gets hotter generating more resistance and less spark to the plugs at a time when you need it. As RMPs drop, resister cools increasing spark to the plugs.
So the resister really controls the spark to the plugs and extends point and coil life and to rectify number 1, you have to build a resister by-pass so you get the full 12-volts pressure to the coil during start ups.