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Does anybody see any reason I can't run the wire for my Holley choke to this key activated terminal on the starter solenoid? Car is a '67 Fairlane.
 

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Old(s) Fart
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Does anybody see any reason I can't run the wire for my Holley choke to this key activated terminal on the starter solenoid? Car is a '67 Fairlane.
The starter solenoid terminal is only energized with the key in the START position, not the RUN position.
 

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In that case, yeah, that's fine. I like to use an oil pressure switch in the power wire so that the choke only heats up if the engine is running.
Which is why most people simply attach it to inlet to the ballast resistor which is only supposed to receive power when the car is in the "run" position on the key switch.
 

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Just to make sure you have it right a test light is your friend,you have an "S" terminal and an "I" terminal connect the electric choke to the "I" terminal. I have both my HEI and electric choke hooked up that way 302 SBF in my '54 Ford.
 

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No. If you turn the key to RUN and don't start the engine, the choke still heats up and opens if you wire it that way.
Which is why the ignition switch has an "ACC" position. This is the position you are supposed to use if the engine is not running and doesn't send power to the ballast resistor or fry your coil while sitting with the motor off and accessories on.

 

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Old(s) Fart
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Which is why the ignition switch has an "ACC" position. This is the position you are supposed to use if the engine is not running and doesn't send power to the ballast resistor or fry your coil while sitting with the motor off and accessories on.
Yeah, so long as the engine doesn't stall...

Look, do what you want. Every factory electric choke uses an oil pressure switch for exactly this reason. GM doesn't waste money installing parts it doesn't have to. Kind of stupid not to run a simple oil pressure switch in series so you never have to think about it again.
 

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Yeah, so long as the engine doesn't stall...
I don't see the relevance.

If the engine stalls and it is hot, and the choke stays on, so what? They are made to stay on when in operation.

If the car stalls and the engine is cold, you're probably just going to restart it again, well before the choke has come up to temp..., so no harm no foul. The choke would not receive current as long as the starter is engaged because the ballast resistor is by-passed in this position.

If stalled, I would be more concerned about frying the coil which is not intended to remain on continuously.
 

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I don't see the relevance.

If the engine stalls and it is hot, and the choke stays on, so what? They are made to stay on when in operation.

If the car stalls and the engine is cold, you're probably just going to restart it again, well before the choke has come up to temp..., so no harm no foul. The choke would not receive current as long as the starter is engaged because the ballast resistor is by-passed in this position.

If stalled, I would be more concerned about frying the coil which is not intended to remain on continuously.

More than once I wished I'd have gotten around to wiring mine to an oil pressure switch. A couple times when tuning idle and it stalled and I didn't go turn the key off right away. Leaving it on for just a minute while messing with the electric fans or something, then starting makes for a crappy cold start. It just makes plain sense to use an oil pressure switch, it's the right way to do it. Someday I'll find my round tuit and do it right.
 

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When I installed the "76 Granada" electric choke on my 68 Ford Fairlane, I just ran the wire to the + side of the ignition coil. I've had no issues.
 

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Joe, this terminal is always hot as long as the key is on.
If you have points ignition, the I terminal on the solenoid is hot with full 12 volts when key is in 'start' position and being back fed by the ignition ballast resister at lower voltage/current when key is in run position and engine running to save the coil from over heating... hooking the electric choke to it may over heat the ballast resister and/or cause almost too low voltage at the ignition coil... or maybe the choke won't get hot enough to fully open...

Definitely don't want to do that on a Chrysler product as they are famous for having the resister burn out anyway and leaving you stranded...

If you have electronic ignition now and feeding direct 12 volts to everything then not a problem...

As 55 Tony mentioned, feeding the choke direct without the oil pressure activation switch can open the choke too quickly if the engine is slow to get started or you delay and do something else first... the oil pressure switch doesn't heat the choke until the engine is running/has oil pressure...
.
 

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Well, lots of suggestions here so, ...

Why not wire it like ford wired it in later years?

Hook the S terminal on the ALTERNATOR to the choke power .Done.
The S terminal is only hot when the engine is running.

That means the choke wont heat until the engine is spinning
 

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The combination of the ballast resistor and coil resistance create a voltage divider circuit.

As Buzz notes, if you connect the choke to the coil (i.e., downstream from the ballast resistor) you do not realize a full 12+ volts, but rather an average of between 6 and 9 volts, depending on the system. You also rob some of the current from the coil/plugs as it now goes to the choke.

Connecting it upstream of the ballast resistor eliminates both of these issues as well as the ability to pull additional current through the ballast resistor burning it out.
 

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Discussion Starter #16
The car has been converted to Duraspark II ignition and will run a '94 F-150 alternator. I just looked at a wiring diagram and it looks like the terminal I wanted to use on the solenoid is powered through the resistance wire - '67 Fairlane doesn't have a ballast resistor. Wiring it through an oil pressure switch sounds good but I like LATECH's suggestion even better. Thanks everyone. Very helpful.
 

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A long, long time ago, Doc Vette had a great solution for this. It used the alternator brown wire (prolly different for your ford) to activate a relay, which switched hot power to the choke coil. This way, the coil only works when the engine is actually running.
 

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IDEALLY, the choke is powered ONLY when the key is in the RUN position (not powered when cranking) AND the engine has oil pressure.

1. You don't want the choke heating during an extended cranking. The choke should not be heating until AFTER you're done cranking it over and the engine is actually running. Thus you connect to a power source that's not active in "Accessory", "Off", or "Crank", it's active only in "Run".

2. Very common for folks to start a cold engine, then let it warm-up while they go back in the house for another cuppa coffee, or take a leak, or whatever. If the engine stalls, you don't want the choke continuing to heat. Thus the oil-pressure switch so power to the choke is interrupted if the oil pressure goes away.

It may be that connecting to the alternator terminal is another way to achieve both goals.
 

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Before you wire it all up, I suggest hooking up the relay coil how you want to and be sure the relay turns on when it should, and the alternator charges how it should. I don't know Fords, but if that wire on the alternator comes from a gen/alternator idiot light, it may not have enough current to operate. And/or it could keep the idiot light on when running.


Thinking while typing, if there is a problem like above, you could get the smallest relay they use in cars (which will draw less current) and if it's not rated for the amperage of the fuel pump, you could have the tiny relay power a larger relay. Sort of getting messy, but I think a little messy at times.
 
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