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8N Ballast Resistor
|Brian F||Does anyone know the actual voltage drop of the resistor when cold? I just replaced the original one on my 48 8N because it wouldn't start when warm. The new resistor wouldn't let it start at all, warm or cold. Input to the resistor was 6.5 volts but output was 1.95, cold. If I jump the resistor it started but when removed the engine would stutter bad. I cleaned the original one up and if I remember I had 4.5 volts cold, not sure what hot was but it started normal until I ran it on the buzzsaw for a few hours. Is it possible low voltage will damage the coil?
|Bob G||It is not the voltage that damages the coil, but rather the current flow(amps) the resistor ohms plus the coil ohms should restrict current flow to about 4 ohms. When cold the ballast resistor has less resistance than when it gets hot.
If you can measure the resistance with an ohm meter it might help.
the resistor cold should be about.3 ohm and 1.0 hot. The coil should measure about 1 ohm.
You may also have a bad ignition switch that will reduce current flow and cause problems. You can check it by making a jumper with clips and just just around it and see what happens.
Your problem really sound more like a weak coil.
|Brian F||Thank you Bob. My issue originally started as a hot restart issue. Cold was fine but after it ran a few minutes it wouldn't start. I installed new plugs and wires, new points and condenser, and cap and rotor while cleaning everything up real well in the process. The engine ran wonderful right after but the same hot restart issue was present. So I followed the wiring and found bare wires on the ign switch and corrosion on the resistor, I replaced both of those. The new resistor was junk right out of the box. I cleaned the old one up and it starts good cold but not yet hot. I have jumped the resistor and it starts fine provided I didn't already flood the engine. You mentioned the coil resistance, how do I measure that, from the input stud to the output spring or the tab? Many thanks!
|Bob G||yes on measuring the coil resistance, I don't really know what you would see if it is bad. I would think that the resistance would be low if the coils were shorted out internally. Let us know what you find. Bo my 8n is side mount distributor so I do not have the coil problem. I have an 8n with a magneto that I am working on. Hope I can get that to work!!!!
|Barrie|| BOB --
Could you tell me a little about the magneto
situation .please and thank you
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