| ken ct. | -- 11-02-2018 @ 1:39 PM |
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Gonna run test of under dash resister on a 36. Will the gauge of the jumper wire with alligator clips carry the load of test. Pretty skinney wire on it.Or do I have to make one with a heaver wire. ??? ken ct.
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| supereal | -- 11-02-2018 @ 2:11 PM |
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The under dash resistor is wound with nichrome wire, the kind that is used in a toaster. As such, the resistance of the unit varies as the current increases to prevent damage to the ignition system by heating. At hiway speeds, it can approach almost red heat. As such, it is a primitive, but effective voltage regulator. The usual problems with the device are caused by faulty connections between the terminals and the winding.
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| TomO | -- 11-03-2018 @ 8:40 AM |
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Ken, I don't know how you intend to test the resister, but if you intend to just jumper around it, I would use a 14 gauge wire jumper. If you intend to check the voltage drop across the resister, just connect your meter leads to the two wires and turn on the ignition switch. You should read about 1.5 volts. If you do not get a reading above 1 volt, tap the starter to see if the points are closed. If you have another method in mind, let us know what it is and we can give you some advice. Tom
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| ken ct. | -- 11-03-2018 @ 8:52 AM |
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I was going to run engine till it heated up and started to run cr*ppy then jump or by-pass with a short alligator clipped jumper wire and see if it runs normal feeding coil full 6 Volts.I can also check with a analog Simson meter whats coming into resister and whats coming out. Does this sound doable ?? ken ct.
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| kubes40 | -- 11-03-2018 @ 9:43 AM |
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Well, kinda... however, if you jump the resister, a full 6v. will go through your coil. Not something you want to do for any extended period of time. Mike "Kube" Kubarth
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| JayChicago | -- 11-03-2018 @ 11:43 AM |
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And, I don't know what that test will tell you. No doubt engine will run better with a full 6 volts supplied, but won't tell you where the problem was. I guess it could tell you this: if you provide a full 6 volts and engine still runs cr*ppy, it pretty much eliminates electrical weakness, you can look elsewhere. To the point of what voltage drop to see at the resistor: When I was trouble shooting my weak spark condition, I was working in the garage with engine stopped, trying in vain to get 3.5 volts at the coil. I tested five or six different resistors. All of them showed very close to a full 3 volt drop. I didn't do any testing with engine running, but I believe theoretically the resistor's voltage reduction changes with engine running, points opening, less current and therefore (Ohm's law) less voltage drop across the resistor. And that explains why I have 3.5 volts to the coil with engine running, but have never been able to get that while working in the garage with engine stopped. Based on what I measured, I think WITH ENGINE STOPPED the resistor's voltage drop should be around 3 volts.
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