power source for electric choke?

Discussion in '1974 - 1978 Mustang II Talk & Tech' started by LXXVICOBRA, Jul 16, 2004.


  1. LXXVICOBRA

    LXXVICOBRA Founding Member

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    Hoping someone here with better overall automotive electrical expertise and knowledge of II wiring, can give me a definitive answer here... to the best, easiest and safest place for getting (key) switched power to run an electric choke. I've searched the other forums on this subject, and it seems that the ideal source varies from year to year, depending on wiring. The car in question is a '76 with 302.
  2. 77sleeper

    77sleeper GO BUCS! Founding Member

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    I tapped off of the winshield wipers, with a relay and created a new bus
  3. Wart

    Wart I'm Mad as HELL and I'M not Gonna Take it ANYMORE! Founding Member

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    Are you sure you want to run 12v into the choke element?
  4. THE COBRAMAN

    THE COBRAMAN pig 'rassler Founding Member

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    The OE setup is sourced from the back of the alternator.

    It provides power only when the alt is turning/generating, thereby presumably preventing damage to the choke coil from overheating (key left on, etc).

    I believe there is also a small opening through the OE 2-barrel choke coil housing to the carb venturi to provide fresh air (vacuum?) to help with heat control.
  5. IICrazy

    IICrazy taken away

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    Thats the one that you want
  6. Wart

    Wart I'm Mad as HELL and I'M not Gonna Take it ANYMORE! Founding Member

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    And it's marked ....... ?
  7. 85GTlover

    85GTlover New Member

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    It is one of the little prongs on the alt I do not think it is marked but, put a wire to find out. There are only a few prongs on the alt....one feeds it from the relay, bigger one....it should be one of the other ones near that one.....many times some do not get used..
  8. THE COBRAMAN

    THE COBRAMAN pig 'rassler Founding Member

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    Stator terminal, marked STA.

    Near as I can tell with it installed.

    White wire on the alt harness.
  9. Wart

    Wart I'm Mad as HELL and I'M not Gonna Take it ANYMORE! Founding Member

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    Isn't there something 'special' about the power coming from the STA post?

    And wasn't there a tube from the choke housing?
  10. jeffnoel

    jeffnoel Founding Member

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    Don't you hate it when people ask questions, when they already know the answer? :bang:
  11. Wart

    Wart I'm Mad as HELL and I'M not Gonna Take it ANYMORE! Founding Member

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    I think you hate it more when you don't know the answer?
  12. jeffnoel

    jeffnoel Founding Member

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    Can someone answer me this, if he's on my ignore list why do I still get an email when he responds to a thread?
  13. cobraii351

    cobraii351 Founding Member

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    I believe it's the STA wire. It is white w/black tracer. At idle you only get between 5-8 volts. It will go slightly higher than this but I don't remember how high it gets. This wire is, as was stated before omly hot when the motor is running. That way you cannot burn up the choke element sitting with just the key on.

    Tim
  14. THE COBRAMAN

    THE COBRAMAN pig 'rassler Founding Member

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    Was being the operative word. Only seen 1 that wasn't rotted off by the heat at the manifold.

    Helps heat the coil, I imagine.
  15. THE COBRAMAN

    THE COBRAMAN pig 'rassler Founding Member

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    I believe the ignore function only blocks the display of posts.

    Not that I can say for sure, I don't have anybody on "ignore". I just read 'em and filter out the garbage in what passes for my brain.
  16. mustang2

    mustang2 New Member

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    You know I gotta say WART does liven things up a bit around here. He either makes you laugh or makes you curse.
  17. cobraii74x

    cobraii74x New Member

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    Not that I don't deny the statements about wart.. but come on guys.. its been said before.. does he have to get busted in every thread? I understand sometimes his posts are a little.. rude, but maybe he is tryin to change his rotten ways and become a better person :D, nuff said.

    I had my elec. choke ran to my coil ? But I guess that isnt such a good idea.. ;) so thats a no-no
  18. 77sleeper

    77sleeper GO BUCS! Founding Member

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    so the choke is not a 12VDC utility, I did not know that, mine has been hooked that way for 12 years
  19. Blue Thunder

    Blue Thunder Active Member

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    Replacing that factory cheesy little (3/16" I think?) rotted-off choke heater tube with a stainless part will eliminate further incidents.

    Wait, forget I said that. What's a choke again?? :lol:
  20. Wart

    Wart I'm Mad as HELL and I'M not Gonna Take it ANYMORE! Founding Member

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    Depends on the type of alternator, whether it's a Delta or a Wye, and if the type of meter reads true RMS.

    In a Wye the STA power comes from the 'common'. Measuring between legs in a Wye gives system voltage, measuring across any leg to common gives ~ 1/2 system voltage.

    In a Delta system STA power is tapped between the diodes of one leg. Also each leg in a Delta creates system voltage. Since STA power is tapped between the diodes this power is half wave rectified so if you put a meter on it and read peak the meter will show system voltage but if the meter is set to read RMS it will show roughly half system voltage, and it will be 'AC'.

    Why is this important? Because when a choke doesn't work someone takes their rinkey dink Craftsman $10 special meter to leads and can't get a steady reading, let alone a 12~14 volt reading, they think somethings wrong. So they start the parts changing frenzy.

    Another reason this is important is it lets you know why not to run 12 v to the stat housing, unless the element is suppose to be ran from 12 to 14 volts, which our era of Fords aren't suppose to be. At least in stock form. I remember more than one choke housing so hot it would about sear off the skin.

    Another important thing, sort of unrelated, is the regulator you get. Idiot Light cars use the STA power to run the field relay. Ammeter cars field relays are ran from the ignition switch. So put a Wye regulator used with an idiot light car in a Ammeter car and wonder why the battery doesn't charge.

    Other things, pulsating lights (v limiter) and such, but I've gone far enough OT.

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