I would leave the resistor in the primary side. It's purpose is to limit current flow in the primary circuitry. In an electronic ignition, transisters are electronically controlled "on-off" switches that replace the mechanical "on-off" switching function the tungstin points used to do. Transisters are manufactured to safely handle "x" amount of current for a given amount of time. Unless you know the specs, you'd PROBABLY do well to err on the side of safety.
This is the first time I've seen this topic. I don't have all the answers. But I do find it some interesting reading. I have some personal brain fodder I'd like to toss into the mix. First, I'm thinking that the resistance in the primary side of the coil, may have something to do with primary saturation time, and in relation to the secondary resistance, coil secondary output. But I could be wrong about that. It's just something that's making me go "hmmmm". When the primary circuit is switched on, current flows through the primary winding of the coil, saturating it with available voltage. It's been a few years since I've seen this drawn out on a chalkboard, but I'll try to speak my mind and anyone can jump in. As current flows through a wire, it creates a magnetic field. When it flows through a coiled wire that magnetism is concentrated. AND... when you pass a magnetic field over a completed circuit it induces the flow of electrons. In an ignition coil, when the primary circuit is switched off, the magnetic field collapses, inducing a voltage in the secondary circuit. Just how much induced voltage is available as the result may have something to do with the resistance in the secondary winding, as well as the amount of saturation in the primary circuit. (gotta have something to work with)
The higher the RPM, the less "time" the primary has to become fully saturated. So then, how quickly this coil primary winding can saturate, and how much heat this unit can tollerate over a period of time, I'd imagine all has to do with the engineering design and manufacturing process. So in my ignorance, if I had to make a decision, I'd choose the coil with the closest primary resistance to the original equipment. Now for the secondary circuit, which is isolated from the primary circuit, it is capable of producing several thousands of volts. But the circuit will only use as much as it takes to overcome the largst resistance in that circuit. Ideally, that will be the spark plug gap. In the '80's we saw some pretty large plug gaps. Some as much as .080" but most were .045" to .060". The reason for these large gaps was to try to ignite the lean air/fuel mixture in a scramble to meet mandated EPA requirements. (leaner is harder to ignite because air is an insulator and there are fewer gasoline molecules to bridge the spark plug gap to allow current to flow.) The result was that the spark plug electrodes were burning down creating an even larger gap, requiring more voltage/current flow, which would start burning the plug wire connections, requiring even more voltage/current, which would start burning through the coil tower in the distributor cap. Tune ups could get expensive. Then Cadillac made a car that required engine removal to change that one spark plug in the back. So they then invented a spark plug that was supposed to last a hundred thousand miles.
Sorry for the rabbit trail. :blush:
Anyways, the secondary circuit will only use what voltage it takes to push current through the highest resistance in that entire circuit. (hopefully the spark plug gap) So something running pump gas with a plug gap of .030" I don't think is gonna require all that much. And it should be capable of saturating the primary winding @8,000 RPM if that's the way you intend to run it. :hihihi:
