67GTCOUPE said:
I would like to know this as well............I used the little connector on the front of the starter solenoid that is closer to the firewall on my 67.........it seems to be hot with engine running?????
Not a good spot because that wire goes back to the coil AND more importantly the coil is connected to the ignition switch via a resistor wire.
Here's what happens when you start the car: 12 volts is obtained from the starter solenoid to power the coil. When you release the key and it goes to RUN, the engine keeps running on power provided from the ignition switch via the resistor wire. This drops the coil voltage down to 9 volts under normal conditions. The impact of this is to provide hotter spark during starting and long coil life during RUN.
Adding the circuit to the electric choke does the following: it adds a branch circuit to the coil circuit in parallel with the coil. During start there is no impact and everything works fine. During RUN however, the coil voltage is lessened by the amount of current drawn by the electric choke and spark output is lower. This could result in your engine missing or sputtering during some conditions. Everything may appear to be okay but it really isn't.
Here's the math of it:
No connection to solenoid:
Coil voltage = 12 volts - voltage drop across resistor wire.
Coil voltage = 12 - (coil current * resistance)
Since the coil draws about 3 amps and the resistor is about 1 ohm...
Coil voltage (RUN) = 12 - (3 * 1) = 9 volts
With connection to solenoid:
Since the coil draws about 3 amps, the electric choke about 1 amp and the resistor is about 1 ohm...
Coil voltage = 12 volts - voltage drop across resistor wire.
Coil voltage = 12 - ((3+1) * 1) = 8 volts.
Note the voltage is not much lower but it is LOWER by 11%. The output spark is therefore 11% lower.
Where should it be connected. Not an easy answer because different car models have different access to switched 12 volt power. On '65/'66 its easy because the resistor wire unplugs. You can add wiring at this point that goes both to the resistor and to the electric choke. On other cars, the resistor wire may be molded into the ignition switch harness connector. In this case, I would use "ACC" voltage at the fuse block. ACC runs all the cars accessories. Refer to the schematic diagram for your electrical system and look at the ignition switch. One of the posts should be labelled ACC. That is the wire you want to tap into.