Alternator and Regulator Wiring

Do not use the coil feed for the choke. The added resistance of the choke will reduce the voltage to the coil and choke from about 7.1 volts to about 6.6 volts, calculated with an engine running voltage of 14 volts. While not a huge drop in coil voltage the coil output to the spark plugs will be reduced by about 7% (1,400 volts on a 20,000 volt coil). The choke is designed to work on 12 - 14 volts and the opening time will be doubled (approximately).

OK, now I am confused again.

Don,
The whole purpose of using the red/yellow hash connection was to get a full 12v off the harness w/o the resistance wire. Why would it drop substantially from 12v to 7.1v within 12" of wire to feed the coil?
Especially using a Pertronix Ignition Coil 45111 Flame-Thrower II Black 45,000 V, .6 ohm.

carguy47 said:

Alright guys, I found the wiring harness connector and I am ready to complete my conversion. Now I have 2 final questions:
First, does someone make a replacement male connector to fit the harness? Or, do I just cut and install insulated spade connectors.
Second, since the PO installed an aftermarket carb, can I pull power from this connection to also feed the electric choke? Or, will it draw to much and negatively impact the coil operation?

Thanks, Bill

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I would suggest pulling electric choke power from the lead used for the Throttle Position Solenoid (TPS) - Circuit 640, Red Wire with Yellow Hash. That wiring is present from 1971-1973 Mustangs, whether a TPS was used in the oem carb or not. Or, you can use the Windshield Wiper Motor's power lead from Circuit #53, Red Wire. Here are some videos that show here those connections are made.

TPS:


Windshield Wiper Motor:



Both circuits are switched full battery/alternator voltage, and protected with a 14 amp fuse (or larger).

OK, I got that and it was discussed. Thx

Don C said:

Yes, circuit #640 is under the hood on all '71s. From what I can tell, the only '71 that used to throttle position solenoid was the 6 cylinder with an automatic transmission. For the rest I believe that it terminates at a white connector.

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Any photo or location to tap into #640. Car is a '71 aftermarket carb so no solenoid installed.

I believe on mine it was a single-socket connector hanging on the firewall, at about the center, and about the height of the intake manifold.

Pic below of the TPS connector at the firewall on a 71 - the red arrow pointing to the white barrel connector. 72 & 73 have it incorporated into the engine gauge harness.

Here is a YouTube video I did on that very subject. I hope you find it useful. The part re: the wiring begins at a bit after 02:25 into the following clip:




I have another video showing an alternative source of 12 volt switch power under the hood at:

Hemikiller said:

Pic below of the TPS connector at the firewall on a 71 - the red arrow pointing to the white barrel connector. 72 & 73 have it incorporated into the engine gauge harness.


View attachment 66998

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Don C, this is where I pulled the power from. See above in red arrow. It gave me a full 12V