engine and drivetrain Where does my resistor wire go?

[esty]

i'm asking about original configuration with a black coil...what are the consequences of wrong resistance...will it blow up the coil, melt the dizzy case, fry points, etc...?

 

[John76]

1 hour ago, esty said:

what are the consequences of wrong resistance

Too much resistance and your car goes much slower.

You may need a front air dam and a rear spoiler....

[John76]

OK....wrong resistance?

A non-resistor coil does not need +12v once the car is started. I recall a coil will last almost indefinitely on 9v to fire the plugs.

However, during cold starts, a hotter spark is needed. The simple solution is to use a non-resistor coil with a resistor wire (or external resistor and relay). This will give you about 9-10 volts to the coil during normal operation =cool running, long life!

During starts, the resistor wire or external resistor is bypassed, allowing +12v to the coil for a hotter spark. This is done with the black/red wire connected between the +terminal on the coil and the #15 terminal on the starter solenoid, or the cut-out relay for the external resistor. 

Or....use a coil with a built-in resistor and rely on other means to help with the cold starts (high compression, EFI, fancy enrichment devices, etc.).

I hope someone can chime in on the trade-offs between too much and too little resistance in the ignition circuit.

[jimk]

1 hour ago, John76 said:

During starts, the resistor wire or external resistor is bypassed, allowing +12v to the coil for a hotter spark.

Not really, the battery voltage drops to around 10V while cranking the engine.  So the coil gets about the same voltage while cranking as during running.  There isn't any "hotter" spark while cranking than while running.

Get an EFI and log the startup and this fact is evident.

[esty]

1 hour ago, John76 said:

 This is done with the black/red wire connected between the +terminal on the coil and the #15 terminal on the starter solenoid, or the cut-out relay for the external resistor. 

 

 

I'm confused now..... i'm trying to get things back in the car and connected after removing a few years ago for paint and  thought i had all this clear in my mind...i have a wire from fuse 12 (the resistor wire) to the + terminal on the coil but not a black/red wire from the starter solenoid...

 

 

the wiring diagram does not show the wire from solenoid to coil + you refer to

 

#9 on the diagram is the starter, #12 is coil

Edited May 5, 2021 by esty

[John76]

Esty,

The wiring diagram you have does not show the resistor in the green wire to the  coil +, or the black/red from the starter.

Here is a sketch of the wiring (note: this is for a '76).

 

[esty]

do i need to add a wire from the solenoid to the + on the coil in addition to the resistor wire already there?...if so, which terminal on the solenoid, top or bottom or does it matter

 

there are 2 wires, crimped together (i assume original) at the solenoid, i don't have a clue where they come from because as you said, the wiring diagram doesn't show them...these wires are both black, no blk/red wire at the solenoid...no loose or unidentified blk/red wire in the bundle going to/from the starter

 

Edited May 5, 2021 by esty