power source for electric choke?

Discussion in '1974 - 1978 Mustang II Talk & Tech' started by LXXVICOBRA, Jul 15, 2004.

  1. Hmmm...if I wasn't totally confused before, now perhaps I surely am!

    Wart: You seem to be very knowledgeable in this matter. I appreciate the time you have put into providing an in-depth explanation about this, for those here that do better understand automotive electrical theory and systems in general, along with those (like me) that have relativly little expertise in the area.

    Thanks too, to everyone else that provided input. Without it, this topic might never have got to this informative point. Wart would have continued asking questions, and I'd have simply wondered why, while trying to pick his brain for more info. Thankfully too, it has mostly stayed on topic, while Wart has been able to show his better side, even to those that might think he didn't have one.

    Clearly, the issue of voltage (as Wart 'mentioned' earlier in this thread) is the main reason the carb manufacturers advise against using power from the alt or the coil as a source...in addition to using another source that might be "hot" even when the engine is not running. I'm glad that you mentioned that too (about voltage), because I'm sure I wasn't the only one here that didn't know, or wouldn't have given it a second thought, had you not pointed it out.
    It would seem that because of so many different ways the auto manufacturers might run wiring circuts on different various models, that the carb manufacturer will not commit to a "recommended source" for power for all applications, but rather make a general statement to the effect that the source must be from an "ignition key activated 12V source."

    However, if Cobraman and Cobraii351 are correct, then it would seem that this is exactly what Ford used for a power source with the electric chokes for II's, and possibly other cars of the era as well. Would that mean, that at least in this instance (due to how II alternators are wired from the factory) that using that wite wire should be acceptable even with an afternmarket piece? Would this be a source that would also keep voltage to an acceptable level as Corbaii351 stated? Also, how do I tell if the alternator is a Delta or a Wye anyway?

    BTW...Yesterday I attended the Syracuse Street Rod Nationals, spending some of my time viewing how others had hooked their electric chokes up. Needless to say, I don't think I saw two cars that did it the same way...and I doubt if the majority knew the (possible) errors and consequences of their ways. I saw some pretty scary fuel line arrangements too, that could easily make matters worse, particularily if something went wrong with a nearby "hot" wire.
    So, even though this whole post is about a somewhat trivial issue of an electric choke, it seems to be a fairly worthwhile topic of discusson after all, (judging by the replies) ...and especially when one considers its relevence to having ignition and fuel systems working safely together in general.
  2. Somethings been bothering me about my post, the ~ (roughly) 1/2 system voltage. It could be closer to .7 peak.

    RMS is a funny creature, it's the voltage that it would be if it were the same voltage all the time. Graphically cut the tops off the peaks and fill in the valleys till the voltage line is flat, that's RMS. In calc it's the area under the plot (same thing).

    Square wave and saw tooth waves can have the same RMS but not the same measured peak.

    Just for giggles I plugged the Fluke into the wall and measured voltage. 118. I then set the meter to capture peak and read 162v.

  3. Sure, I can answer it.

    What do you think you have to do to keep from seeing the email notifications?

  4. Why do you think I was asking leading questions?

    Theres a simple answer but I've supplied enough information for it to be figured out.

    Seems so.
  5. RMS .707 baby, now we are in my realm! in theory, household is supposed to be regulated to ±169VAC

    RMS Value is equivalent to a DC voltage that would provide the same amount of heat generation in a resistor as the AC voltage would if applied to that same resistor
  6. Mark,

    Thanks for the detailed explanation. It's been a long time since I played with lower freq. A/C stuff. I live in a mostly RF world at work, and that is starting to move to digital. That and I didn't realize there were 2 different ford alternator wiring configurations. It's always good to learn new stuff.

    Now a question. I am using the STA line to power my Holley choke, and a small relay in series with a temp switch for my electric fan. At certain idle speeds the voltage was rides a little too low for the 12 volt relay to stay latched. It almost sounds like a buzzer. I was thinking of making a small +5 volt regulator circuit and use a small 5 volt relay to trip the larger main fan relay. Any comments/suggestions? I'd appreciate any help or advice.

  7. although i have not run an electric choke in years, i am finding this thread pretty interesting.

    i know someone out there wants to say: "for those of us that are electrically illiterate, what would be a good source for the power besides the the post on the alternator".

    oh and i am one of them.
  8. I've seen it low as 162 and as high as 175. I'm sure I would have seen greater deviations if my hobby were staring at test equipment measuring outlet voltage.

    I use to think 'quality power' was just a phrase used by marketers for a utility, turns out there truely are different qualities of power.

    I was going to leave amperage out of this.

  9. Are you sure it's a decrease in voltage, or could it be a lowering of frequency? Is your relay DC or AC? Are you running underdrive pullies? Delta or Wye? (I'll bet delta)

    It's my guess unless you build a regulated power supply or use a relay with a coil core retentive enough to keep the contacts closed at a low cycle your problems will continue.

    Funny thing about relay coil ratings, the voltage marked is the max voltage that should be ran through the coil, not the minimum when the relay goes active.

    This has gotten me all curious, now I want to take a ruler and meter to an alternator and start measuring.
  10. I did a little more looking and it seems the STA terminal on some Wye wound alternators get their power from between the diodes from one leg of the stators, just like the Deltas.

    Oops. And, you have to love Ford.

    Almost have to take the alternators apart to see exactly what you have.
  11. To be honest with you I never really checked to see what the freq. was. I had really just ASSumed that it was DC and never gave it much thought. But I am going to have to look a little closer now. As for the type of Alt. How would I go about checking? I'll admit I'm quite out of my element when it comes to "industral wiring" talk. I've spent too many years doing RF ands now digital with my head in a PC.
    I know that relays have all kinds of minimum voltage specs. At faster idle the relay I was using pulled in just fine, but when I adjusted the carb and got things setup a little better the warm idle was just at the threshhold and it started to buzz a little. I just found a 6v automotive relay inthe Newark catalog that I hadn't noticed before. I might do that and see how that work too. I also need to see what the max output voltage or the STA terminal is. I guess it's set the Fluke on peak hold and snap it to 6K and see what I get.

    The only trouble with the ford diode pack is that most of them are epoxy dipped and you can't really see what is going on inside. I bought a 105Amp upgrade kit from these guys http://www.alternatorparts.com/ and believe me I can see the "AMP" guage move. I knew the stock ALT was not really up to the task of driving the Taurus fan. I didn't need an engine brake when the fan kicked on. But I also didn't want the fan kicking on while the engine was turned off. That's why I was using the STA line to kick a relay that with a temp switch in series with the contacts would trip the "BIG" relay to turn the fan on.

    Thanks again, I like learning new stuff.

  12. Wart, Is your proffesion a teacher by any chance, a shop teacher I'm guessing? Just kind of get the drift you are. You make them think of the answer, instead of giving them the answer.