Originally Posted by BioTex
You start off saying there isn't any difference. Then you say points coils have a built in resistor and the others don't.
That seems like a huge difference to me!
So, if a person happens to have a resistance wire, AND uses an internally resisted coil then they would have a double resisted ignition system. Reason for my question is wondering what would happen to the voltage?
See where I'm going?
You can buy 'Internally Resisted' coils,
Or you can buy coils where you need an external resistor.
They usually have 'Internal Resistor'
or 'Do NOT USE WITH ELECTRONIC IGNITION
' printed right on the side of them...
And you have to remember,
There hasn't been much made since '75 that had an serious internal resistor built into it from the factory,
So you REALLY have a hard time tracking down an internally resisted coil these days for the farm equipment that used them...
You have to remember,
MOST of the internally resisted coils were for farm equipment that sat for two or three seasons every year,
Since most farm equipment didn't use 'Resistor Wires' (and I don't know why),
The ceramic block type resistors were use...
So they got wet, rained in , frozen, rusted, ect.
The ceramic block type resistors didn't live in farm equipment because of moisture, lack of use, weather, farm chemicals, ect.
SO 'SOME' farm equipment used internally resisted coils, it got the resistor out of the weather ....
IF you run in to one these days, go play the lottery since you are on a lucky streak!
It's like mentioning CJs used a closed knuckle Dana 25 or 27 in the past,
And you MIGHT see one someday,
But you shouldn't run into one from about 1970 forward to present day...
Low production number and attrition have pretty much taken all the old closed knuckle CJ diffs,
The rest people don't notice the difference,
So if someone finally DOES notice one, they have a ton of questions...
Chrysler is the only CAR company I know of that used internally resisted coils in any numbers, and that was only for like two years before they dropped it...