Testing voltage to the points on the Sportfour Imperial

[Buccaneer]

Gary, I looked up this resistor before, but I seen specs that
the resistance was only around 1.5 ohms.
Now I see in some specs that it’s listed two ways as shown
below. I’ll have to study up on what this actually means.
Thanks!
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Standard RU12

Ballast Resistor

Specification:

Operating Resistance: 4.75-5.75 ohms At 25 Degrees Celsius
Cold Resistance (ohms): 1.15-1.38

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Prepare to be boarded!

[Tubs]

Buccaneer wrote:

From what I know, points ignition systems with 12 volt systems,
had a ballast resistor, or other type, usually around 1.7 ohms,
depending on the type of coil used. This was to lower the voltage,
and hence the current going through the points so they didn’t
burn up.
The generator will change the equation somewhat I presume,
when it’s putting out 13.5 volts, etc.,
I read somewhere that nine volts to the points would be okay,
but I’m currently at 10 volts.

As you have stated, the ballast resister is to keep the points from burning up in a12 volt system. However it is bypassed when starting. This is done through the ignition switch in Chrysler products, and from the starter solenoid in GM products. I believe Ford did it from the starter solenoid as well. This is to aid in starting because of the load on the system when the starter is cranking.

A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.

[Buccaneer]

Tubs, no such voltage bypass on the Owen Dyneto setup.
Perhaps by design, the ignition voltage runs a little higher
on these units, to insure there’s adequate voltage for starting?

Prepare to be boarded!

[Gary Haight]

What about using a dual ballast resistor like the Standard Ignition RU-12. I believe one side is approx. 5 ohms and the other side is approx. 1.2 ohms. You could use the 5 ohm side and if needed, add the 1.2 ohm in series. Just a thought. They are not too expensive.     In the autos, the ballast resistor was used to cut the voltage to the coil in the run position only.  The coil would get 12 volts during cranking for a hotter spark and in the run position, the coil gets the ballast voltage of approx. 9 volts.

[Tubs]

From your video, there is no issue with it starting. Your focus should be on protecting the points.     

A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.

[Author]

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