Couple of questions

Good morning all!

In my quest to recreate my '73 Mach back to OEM specs (nuts, bolts, missing items), and to ensure everything works as it should, can anyone tell me:

1. Engine to firewall ground strap, mine's missing - What type of wire is used? I know that it bolts to the back of passenger side head and then to where on the firewall? I couldn't find any existing holes on the firewall directly behind the head. Only thing I saw was a somewhat loose screw that holds the clamp that supports the brake line lower on the firewall in that area.

2. I have a Holley 4160 carb w/ electric choke. Prev owner connected the 12v directly to the coil. According to the Holley installation manual this is a huge no no as it could cause a myriad of issues with the ignition system, gauges, etc.. Where is the best place to connect the choke to a key activated 12v source?

Thanks much for y'all support!

And yes, I did do a search on the forum(s) for these questions prior to my post...

Hmmm.

1)   Mine is a 71 and I do not recall a ground strap to the engine as being original.  Maybe someone else has better guidance there.

2)  Electric Choke for the Holley, I have the same question.  I am thinking of running a cable to the switched side of the starter solenoid.  Then I don't tax the factory harness any and I get a safe 12v to the choke.  But I am NOT an electrical guy, so I want to see what's wrong with that.

kcmash

Question 1

There is not ground strap on any of them. I added a couple to mine. The original ground cable had a  tab that bolts to the bottom screw holding the voltage regulator and then goes to the block under the RH head behind the alternator. I have a braided ground going from engine to frame and another from frame to valve cover bolt. A ground is a horrible thing to waste.

Question 2

I expect Midlife to have the right answer for this one. I would expect it to be any key initiated 12 V. source other than ignition.

The switched side of the starter solenoid provides 12 volts only when the key is in start position. For a '71 you'll likely have to run a new wire from inside the car to the choke. Some of the later models had a wire running to the throttle position solenoid that could be used.

Great information, thanks to all for your replies!!!!

You can hook your electric choke to the stator - "STA" terminal of the alternator. It only has power with the engine running, so the choke won't be energized if you just have the key on, which is how the factory ran the power. 

https://www.allfordmustangs.com/forums/attachments/classic-tech/157712d1339536931-1971-alternator-regulator-wiring-assistance-alternator-ford.jpg

Here's what the factory ground cable looks like. The bracket midway is the tab that CMM is talking about. It's crimped directly to the conductor in assembly. If yours is missing this, you can run an auxiliary ground from the engine to the fender apron, or battery to fender apron. Either will serve the same purpose. 

The stator is an ideal place to connect the choke to, convenient location under the hood, and energized only when engine is running. However, the stator output provides only 6 to 8 volts, which causes the choke to take longer to open. The Ford electric chokes were designed for the lower voltage.

You can hook your electric choke to the stator - "STA" terminal of the alternator. It only has power with the engine running, so the choke won't be energized if you just have the key on, which is how the factory ran the power. 

https://www.allfordmustangs.com/forums/attachments/classic-tech/157712d1339536931-1971-alternator-regulator-wiring-assistance-alternator-ford.jpg

Here's what the factory ground cable looks like. The bracket midway is the tab that CMM is talking about. It's crimped directly to the conductor in assembly. If yours is missing this, you can run an auxiliary ground from the engine to the fender apron, or battery to fender apron. Either will serve the same purpose. 

Click to expand...

The stator is an ideal place to connect the choke to, convenient location under the hood, and energized only when engine is running. However, the stator output provides only 6 to 8 volts, which causes the choke to take longer to open. The Ford electric chokes were designed for the lower voltage.

Click to expand...

I'm late to the posting gate, but these two gentlemen are correct regarding the Stator post for electric choke.

use the stator wire to trip a relay for 12 volts pulled from the battery. Add yourself a small 6 circuit fuse block and if you need a switched source in the future(like for an upgraded ignition, electric fan, etc you will have it. Will not work for an efi electric fuel pump though unless you use a keyed power source as it won't prime the engine.