Upgraded Coil, now Alternator Light on Options

[Tastyplacement]

914world, please save me again from my mediocrity.

2316cc T4. I used to have an Empi distributor with Bosch blue coil. I upgraded to pertronix 45kv 0.3 ohm coil and pertronix distributor. Great spark now, easier starts, but my alt. light stays on. Previously, i would have to get rpm over 2500 to make light go off, now no spike in rpm will make the light go off.

I have led bulbs in dash, and i am willing to do the 100 ohm resistor mod to the alt light if that is necessary.

[Tastyplacement]

Thanks everyone...

So weird: changed back to incandescent bulb. It shows not very bright when ignition is on. After starting engine it dims as RPMs increase, but never really goes out.

The previous owner had done a strange thing: he had wired a resistor in SERIES with the alternator light--not in parallel as the tutorials indicate to "excite" the alternator. I have that resistor removed right now.

[pbanders]

Thanks everyone...

So weird: changed back to incandescent bulb. It shows not very bright when ignition is on. After starting engine it dims as RPMs increase, but never really goes out.

The previous owner had done a strange thing: he had wired a resistor in SERIES with the alternator light--not in parallel as the tutorials indicate to "excite" the alternator. I have that resistor removed right now.

Suggest you check out your overall charging system using the reference I provided. The light is on when there is a voltage across it. When the key is on and the car is not running, the battery voltage (~12.75 V) is applied to one side of the light, the other side is connected to D+ on the voltage regulator, and the current path is through the a diode in the voltage regulator to ground (i.e. 12.75 V - 1.2 V = 11.55 V across the bulb). In normal operation, when your alternator is turning at higher than the zero-ampere speed, it produces voltage (~14 V, determined by the voltage regulator), and 14V is present at D+. The voltage dropped across the light now is now about 0.4 V, as the battery voltage comes up about 13.6 V while charging.

If you can actually see the incandescent bulb glowing after the car is running, it's telling you that the voltage difference between the battery and the alternator is considerable, How much? I did a little experiment, I have one of the instrument incandescent bulbs, and a variable voltage power supply. When you put 1.3 V or less across the light, you can't see the filament glow. You have to put at least 2.0 V on the light for it to glow very dimly. At 3.0 V and above you probably can begin to see it at night.

What's that's telling you is that you've got a problem with either your battery, voltage regulator, or alternator. If you follow the tests in the reference I provided, you can isolate the problem quickly. If you have a spare, good voltage regulator, you can swap it in and see if that fixes it. If not check the battery, you can either do this yourself or you can have it done at an auto parts store. If that checks out, then it's your alternator, and you can do the tests to identify where the problem is.