• Welcome to ClassicBroncos! - You are currently viewing the forums as a GUEST. To take advantage of all the site features, please take a moment to register. It's fast, simple and absolutely free. So please join our community today!
    If you have problems registering or can't log into your account, please contact Admin.

Electric Choke wiring

wal1210

Contributor
Newbie
Joined
Aug 11, 2017
Messages
34
So I got a pair of James Duff headers (look and fit great btw) and I'm changing the choke on the original carb (motorcraft 2100) to an electric Choke. My question is, where should the wire go? I know many people have said to wire it to the back of the alternator at the s position but I only have a grd and a bat terminal on the back of the alternator. Will either of these work? The ignition module is close by, can I wire it there?
 
OP
OP
W

wal1210

Contributor
Newbie
Joined
Aug 11, 2017
Messages
34
I'm unsure, I have never changed it in the year I've had it but who knows what the PO did. Is there a way to tell?
 

bronconut73

Bronco Guru
Joined
Aug 7, 2012
Messages
9,916
Do you see a white wire in your alternator harness. On mine that was the wire I tapped into.
 

blubuckaroo

Grease Monkey
Joined
Jun 11, 2007
Messages
11,795
Loc.
Ridgefield WA
You'll need to find out what alternator you have. The factory chokes were designed to operate on the seven volts from the stator "S" terminal on the alternator.
 
OP
OP
W

wal1210

Contributor
Newbie
Joined
Aug 11, 2017
Messages
34
It has a black wire from the bat terminal and an orange wire to the grd terminal. I'll post a picture tomorrow
 

markw

Contributor
Bronco Guru
Joined
Sep 10, 2009
Messages
2,047
I've been reading up on this. I just changed the carb on my boat to an Eddlebrock with electric choke. Eddlebrocks' instructions say to wire to keyed switch. No mention of wiring to alternator. Much dissent on this online.
 
OP
OP
W

wal1210

Contributor
Newbie
Joined
Aug 11, 2017
Messages
34

Attachments

  • IMG_20180617_091950.jpg
    IMG_20180617_091950.jpg
    120.1 KB · Views: 88
  • MVIMG_20180617_091911.jpg
    MVIMG_20180617_091911.jpg
    115 KB · Views: 53

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,833
I've been reading up on this. I just changed the carb on my boat to an Eddlebrock with electric choke. Eddlebrocks' instructions say to wire to keyed switch. No mention of wiring to alternator. Much dissent on this online.
Those instructions are for an Edelbrock, the original question is in regards to a Motorcraft. Different designs.
 

904Bronco

Contributor
Bronco Guru
Joined
Sep 28, 2004
Messages
5,749
Loc.
San Martin, CA
So you have a standard 40Amp (by the numbers stamped, but not always a true indicator) 1G alternator.

With the engine running that terminal with the black ring around it should be the stator. (might even say it on the case) With the engine running there should be voltage at that point and no voltage when not running, key off)

Yes, I suppose you could hook the choke up to an ign circuit for power. That was how my 68 was done, with a 72 Autolight carb on it. They used a relay though...
 

Crush

Contributor
Bronco Guru
Joined
May 30, 2007
Messages
3,463
Loc.
Greenbottom, WV
i have read that the chokes work off of 6 volts not 12 so it should go to the factory s connection
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,833
The S terminal only has voltage to it when the engine is actually running. If the engine stalls during warm up, the alternator stops, the S terminal goes to nothing, and the choke stops opening. Those engineers back in the day were pretty smart.

If you just hook it to the ignition the choke will warm up and open regardless of the engine running or not. Key on and no start, choke will still open up. When things work right, no problem. But when things don't work, it becomes another problem to deal with. Get a winter no start, next thing that happens is the choke is also open. So now you are fighting two problems and not knowing it.

If you take a choke calibrated to warm up on stator voltage (less than 12V) and you put 12V to it, it will warm up faster. The choke will open too quick. The other way can also happen, a choke that is expecting 12V (Edelbrock) is only given 7V off the Stator post, it will warm up slower.

I like the Stator engineering solution. Even on chokes that are 12V, well the choke is on a little longer. A little extra fuel wasted. I still think it is better engineering. Says a guy that has a hand choke on every carb I have owned for the past 2 decades.
 

markw

Contributor
Bronco Guru
Joined
Sep 10, 2009
Messages
2,047
Well, we followed the Eddlebrock instructions and it works well. Now, this is on a boat which makes manual choke difficult otherwise that's what I'd do and avoid all this wiring stuff.
 
Top