Engine wiring help

blkulis

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I am putting the 72 car back together now. I installed an edelbrock carb with electronic choke. It has a red and black wire from the carb. Many of you have said that I can use the red/yellow short plug in to feed to the electronic choke. Can I use a plug in to go from the red and black to the red/yellow strip short plug in? If so, where do red and black go? Or should I run the black wire to a ground and red to the Red/yellow connection? Also, would you know where to get the plug in connector??

Carb to Engine feed.jpg

 
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Don C

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The red/yellow wire will provide key switched 12 volts whenever the key is on. However, this will mean there are times when the choke starts opening before the engine starts. A better option is to run it to the STA terminal on the alternator. That way the choke only receives power when the engine is running and is how Ford wired electric chokes. Run the ground wire to one if the hold-down screws on the choke housing.

 
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rutkak

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Mount the black wire to one of the screws on the choke housing and run the red wire to the hot side of your ignition coil if you get 12Vs. That's how I set mine up and haven't seen any issues. Edelbrock says not to do it, but I have no idea with the STA terminal is on my 1-wire alternator.

 

Don C

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A word of caution, most of our cars have a resistance wire or a ballast resistor before the ignition coil, which reduces the voltage to the coil. Adding more load to it will further reduce the voltage to the coil.

 

rutkak

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I strongly concur with Don C about potentially dropping voltage on the coil. My alternator doesn't have a STA terminal though so I'm stuck with limited options. The right answer is to find a keyed 12V source and run it to that. I recommend seeing if you have any extra wires / plugs in your engine then checking them with a multi-meter to see if they will suffice. Interestingly, I have a plug that has a red and separate brown wire that has never been hooked up to my car to I may splice the choke to the 12V keyed red wire. The brown wire's voltage is bizarre so I'll stay away from that.

If that won't work, you can use the hot side of the ignition coil.

 

midlife

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There is a wire associated with the oil, temp, and coil lines that is used to power up the carb anti-stall solenoid; that line is hot only when the key is in the RUN position. On a 71, it is a separate bullet plug; on 72/73's it is the 4th pin on the oil/temp/coil flat plug.

 

rutkak

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There is a wire associated with the oil, temp, and coil lines that is used to power up the carb anti-stall solenoid; that line is hot only when the key is in the RUN position. On a 71, it is a separate bullet plug; on 72/73's it is the 4th pin on the oil/temp/coil flat plug.
Midlife, that's great info. Not to hijack this thread but I ended up using the red wire that was in my engine mentioned above. I spliced in my electric fan sensor power and electric choke. No issues on operation. I may separate those and later use the 4th pin to break those two out into separate lines.

Although I checked it quickly, when I had my car keyed and the electric fan sensor + electric choke were connected to my coil I thought the voltage was about 9.5V. After I separated them it was much higher to 12+V. I hadn't seen any issues with the operation of the car previously but I figured I didn't want to chance it.

 

Mister 4x4

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There is a wire associated with the oil, temp, and coil lines that is used to power up the carb anti-stall solenoid; that line is hot only when the key is in the RUN position. On a 71, it is a separate bullet plug; on 72/73's it is the 4th pin on the oil/temp/coil flat plug.
Excellent! Then I did mine right. ::thumb::

 

Paul of MO

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Mr. Midlife,

I have a question about the same thing.

The 73 we are putting back together appears to have the origional harness but the wire bundle that come off the main engine loom and goes around back to the oil pressure sending unit for a guage and then travels on around to the electric choke has a additional single wire flat connector just like the one for the choke.

What is this 2nd flat connector for?

The loom that travels along the top of the manifold toward the A/C also has a single wire flat connector that I think is for the low/high idle solinoid.

I have several core 302's and 351's out of 71-73 mustangs and I always keep the factory harnesses with them. None of these have this extra female spade type connector.

Thanks in advance!

Paul

 

midlife

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Mr. Midlife,

I have a question about the same thing.

The 73 we are putting back together appears to have the origional harness but the wire bundle that come off the main engine loom and goes around back to the oil pressure sending unit for a guage and then travels on around to the electric choke has a additional single wire flat connector just like the one for the choke.

What is this 2nd flat connector for?

The loom that travels along the top of the manifold toward the A/C also has a single wire flat connector that I think is for the low/high idle solinoid.

I have several core 302's and 351's out of 71-73 mustangs and I always keep the factory harnesses with them. None of these have this extra female spade type connector.

Thanks in advance!

Paul
I'm going by the very few gauge harnesses I've seen for 71/73's and the schematics. I've not seen what you've described; it may be a set-up for an electric choke that some of these cars may have had.

And if you call me Mr. Midlife again, I'll check your shorts in a way you may not like! My name is Mid or Midlife. *G*

 
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Totalled

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IIRC, one was hot, and one was ground for the original 73 carb's choke.

 
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