Electric choke install - experience and opinions

Matt Colie

Matt Colie

Well-known member
Aug 15, 2008
11,101
807
113
South East Michigan near DTW
With the hot part of the manifold blocked, I have installed an electric choke heater.

I am looking for a power source. I do not have an oil pressure switch (yet).

If I tap the ignition circuit and have an "No Start" then the choke will be opening too early.
If I tap the output of the alternator output, then I have to correct for the 0.6V that would otherwise open the choke sooner.

What insight can anyone provide to make this choice?

Thanks,

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
 
Matt,
Back when I was running a Carb, I tapped the alternator with...of coarse... a fuse. Took a couple of cold starts to get it adjusted right. After that,
no issues. JWID
--
Larry
78 Royale w/500 Caddy
Menomonie, WI.
 
>
> With the hot part of the manifold blocked, I have installed an electric choke heater.
>
> I am looking for a power source. I do not have an oil pressure switch (yet).
>
> If I tap the ignition circuit and have an "No Start" then the choke will be opening too early.
> If I tap the output of the alternator output, then I have to correct for the 0.6V that would otherwise open the choke sooner.
>
> What insight can anyone provide to make this choice?
>
> Thanks,
>
> Matt
> --
> Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
> Electronically Controlled Quiet Engine Cooling Fan
> OE Rear Drum Brakes with Applied Control Arms
> SE Michigan - Twixt A2 and Detroit
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
I use the electric choke version that uses a thermister mounted under an
intake bolt to determine how to set the choke. It opens the choke as the
engine heats, the way it should. I got power from the distributor, I seem
to recall.

Here’s an old pic that shows the wire and the sensor:

http://www.gmcmhphotos.com/photos/intake-manifold-pics/p26360-installing-aluminum-intake.html

NAPA used to call this the 21603, but that doesn’t work any more. I found
what may work as an alternative.

http://www.carburetor-parts.com/Electric-Choke-Conversion-Kit_p_3885.html

Rick “wondering why these are so hard to find” Denney

> With the hot part of the manifold blocked, I have installed an electric
> choke heater.
>
> I am looking for a power source. I do not have an oil pressure switch
> (yet).
>
> If I tap the ignition circuit and have an "No Start" then the choke will
> be opening too early.
> If I tap the output of the alternator output, then I have to correct for
> the 0.6V that would otherwise open the choke sooner.
>
> What insight can anyone provide to make this choice?
>
> Thanks,
>
> Matt
> --
> Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
> Electronically Controlled Quiet Engine Cooling Fan
> OE Rear Drum Brakes with Applied Control Arms
> SE Michigan - Twixt A2 and Detroit
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Rick Denney
73 x-Glacier 230 "Jaws"
Off-list email to rick at rickdenney dot com
 
Not sure if this applies to a 1973, but a good place to pick up a battery with key on is on the driver’s side of the heater box. The yellow lead going to the blower motor resistors.
On the later models many of us have cut this yellow wire to eliminate the blower from blowing all the time.

Emery Stora
77 Kingsley
Frederick, CO

>
> With the hot part of the manifold blocked, I have installed an electric choke heater.
>
> I am looking for a power source. I do not have an oil pressure switch (yet).
>
> If I tap the ignition circuit and have an "No Start" then the choke will be opening too early.
> If I tap the output of the alternator output, then I have to correct for the 0.6V that would otherwise open the choke sooner.
>
> What insight can anyone provide to make this choice?
>
> Thanks,
>
> Matt
> --
> Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
> Electronically Controlled Quiet Engine Cooling Fan
> OE Rear Drum Brakes with Applied Control Arms
> SE Michigan - Twixt A2 and Detroit
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
No, I got power from the ignition switch, using a wire that goes to the oil
pressure switch and the fuel pump. Needed to look at my old picture more
carefully!

Rick “not home to look” Denney

> I use the electric choke version that uses a thermister mounted under an
> intake bolt to determine how to set the choke. It opens the choke as the
> engine heats, the way it should. I got power from the distributor, I seem
> to recall.
>
> Here’s an old pic that shows the wire and the sensor:
>
>
> http://www.gmcmhphotos.com/photos/intake-manifold-pics/p26360-installing-aluminum-intake.html
>
> NAPA used to call this the 21603, but that doesn’t work any more. I found
> what may work as an alternative.
>
> http://www.carburetor-parts.com/Electric-Choke-Conversion-Kit_p_3885.html
>
> Rick “wondering why these are so hard to find” Denney
>

>
>> With the hot part of the manifold blocked, I have installed an electric
>> choke heater.
>>
>> I am looking for a power source. I do not have an oil pressure switch
>> (yet).
>>
>> If I tap the ignition circuit and have an "No Start" then the choke will
>> be opening too early.
>> If I tap the output of the alternator output, then I have to correct for
>> the 0.6V that would otherwise open the choke sooner.
>>
>> What insight can anyone provide to make this choice?
>>
>> Thanks,
>>
>> Matt
>> --
>> Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
>> Electronically Controlled Quiet Engine Cooling Fan
>> OE Rear Drum Brakes with Applied Control Arms
>> SE Michigan - Twixt A2 and Detroit
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
> --
> Rick Denney
> 73 x-Glacier 230 "Jaws"
> Off-list email to rick at rickdenney dot com
>
--
Rick Denney
73 x-Glacier 230 "Jaws"
Off-list email to rick at rickdenney dot com
 
Matt, I tapped the alternator too, worked great all the way up till I pitched the carb for EFI. Follow closely the MM for the carb choke set up and
you should not have to adjust after you install accept for the high idle speed.

Jon
--
Jon Payne
76 Palm Beach
Westfield,IN
 
Hmmm...

I also installed an electronic choke and just tapped into a "hot with ignition" fuse in the fuse box. I don't recall which one.

But now you guys have me re-thinking that. Might be opening quicker than designed - especially with a no-start.

But... I'm in Southern California. Is it an issue that's of more concern with COLD weather ??

Thanks,
Steve W
1973 23'
Southern California
 
Tap alternator and run it through a relay so choke gets normal voltage. Use center terminal for relay coil and a fused feed off the engine side of the
isolator to relay contacts and on to heater. All right there with isolator as a junction block.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
We take the power from the alternator at the Isolator center terminal.

On Thu, Aug 2, 2018 at 2:40 PM, John R. Lebetski
wrote:

> Tap alternator and run it through a relay so choke gets normal voltage.
> Use center terminal for relay coil and a fused feed off the engine side of
> the
> isolator to relay contacts and on to heater. All right there with isolator
> as a junction block.
> --
> John Lebetski
> Woodstock, IL
> 77 Eleganza II
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.appliedgmc.com
1-800-752-7502
 
I've run an electric choke for several years since I blocked the crossover passage. I just ran a wire from the alternator output through a fuse and
over to the choke. (Incidentally, this is how I provide a safety cutoff for my electric fuel pump too. If the alternator stops charging, the pump
shuts off.)
As for the voltage difference between battery and alternator(due to the drop across the isolator diodes), a 5% difference (less than 1V over 14V)
isn't worth thinking about.
JWID
Rick Staples
'75 Eleganza
--
Rick Staples, '75 Eleganza, Johnstown, CO

"Advice is a dangerous gift, even from the Wise to the Wise, and all paths may run ill." -Tolkien
 
How do you activate the pump for starting?

On Thu, Aug 2, 2018 at 8:11 PM, Richard H Staples
wrote:

> I've run an electric choke for several years since I blocked the crossover
> passage. I just ran a wire from the alternator output through a fuse and
> over to the choke. (Incidentally, this is how I provide a safety cutoff
> for my electric fuel pump too. If the alternator stops charging, the pump
> shuts off.)
> As for the voltage difference between battery and alternator(due to the
> drop across the isolator diodes), a 5% difference (less than 1V over 14V)
> isn't worth thinking about.
> JWID
> Rick Staples
> '75 Eleganza
> --
> Rick Staples, '75 Eleganza, Johnstown, CO
>
> "Advice is a dangerous gift, even from the Wise to the Wise, and all paths
> may run ill." -Tolkien
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.appliedgmc.com
1-800-752-7502
 
Matt,
If you are worried about the higher alternator voltage at that the isolator, simply install a small power diode in series with the choke. This will
bring your voltage back in line with normal chassis voltage. Measure the DC resistance and use Ohms Law to calculate the current rating required of
the diode.

Come to think of it though, the alternator output is rectified 3 phase at the isolator center terminal with the peak voltage roughly 0.7 v higher than
battery voltage. On the battery side of the isolator it will be pure DC. So I'm thinking the RMS voltage out of the alternator might actually be less
than the battery voltage, meaning your choke might actually react slower. Things that make you go Hmmmmm....

--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
 
Why is it of any concern? The choke stove, that resistance wire, the one
that heats up the spring that actually moves the choke plate, varies with
temperature.
The single most important issue here is WHEN it starts to heat up.
If it starts heating the instant the ignition circuit is turned on,
SOMETIMES it will open the choke plate a bit early. If that happens and the
engine has not started yet, the engine might be difficult to start OR die
after starting, or stumble until the engine warms up a bit.
SO if that is the case, ADJUST IT A BIT RICHER. If that doesn't suit
you as an appropriate fix, then power the choke from a source that only
receives power after the engine starts. IT REALLY IS NO BIG DEAL.
If you look on the plastic housing, you will see a double ended arrow
with the words rich and lean nearby. Some of the old stuff used to say
summer and winter instead. That would indicate that someone should adjust
the choke seasonally. Were they trying to tell you something? I dunno.
Jim Hupy
Salem, Or
78 GMC ROYALE 403 with an electric choke stove powered off the center tap
of the isolator. Works year round for me in Or.

> Matt,
> If you are worried about the higher alternator voltage at that the
> isolator, simply install a small power diode in series with the choke. This
> will
> bring your voltage back in line with normal chassis voltage. Measure the
> DC resistance and use Ohms Law to calculate the current rating required of
> the diode.
>
> Come to think of it though, the alternator output is rectified 3 phase at
> the isolator center terminal with the peak voltage roughly 0.7 v higher than
> battery voltage. On the battery side of the isolator it will be pure DC.
> So I'm thinking the RMS voltage out of the alternator might actually be less
> than the battery voltage, meaning your choke might actually react slower.
> Things that make you go Hmmmmm....
>
> --
> Bruce Hislop
> ON Canada
> 77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
> http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
> My Staff says I never listen to them, or something like that
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
> Matt,
> If you are worried about the higher alternator voltage at that the isolator, simply install a small power diode in series with the choke. This
> will bring your voltage back in line with normal chassis voltage. Measure the DC resistance and use Ohms Law to calculate the current rating
> required of the diode.
>
> Come to think of it though, the alternator output is rectified 3 phase at the isolator center terminal with the peak voltage roughly 0.7 v higher
> than battery voltage. On the battery side of the isolator it will be pure DC. So I'm thinking the RMS voltage out of the alternator might actually
> be less than the battery voltage, meaning your choke might actually react slower. Things that make you go Hmmmmm....

Bruce,

I had considered the "Diode Trick". Kind of like somebody using a bridge to slow down the wipers......

Speaking of things that make you go Hmmmm....
You are and RF Guy, so you may not know that the AC component of the output of an alternator is massively non-sinusoidal. This is intended and it is
why the pole faces of the field are trapezoidal. With a field face like that, the AC output is almost trapezoidal, too. So trapezoidal that the RMS
is real close to the P-P.

Right now, I am planning to put an inline fuse at the center of the isolator and a diode and go with that as it is the simplest and the fewest added
parts.

Thanks,

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
 
Sounds like center terminal is fine and not over engineered. I have to put a scope on the alt output. The 3 phases overlap so below a certain
amplitude you have smooth DC. The peaks of the non overlapping areas would be trap or triangle. In a car where battery is parallel I assume it looks
pretty smooth. Not sure with the isolator how it looks on alt side.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
Jim H,
I agree with your comment.

Sent from my iPhone

>
> Sounds like center terminal is fine and not over engineered. I have to put a scope on the alt output. The 3 phases overlap so below a certain
> amplitude you have smooth DC. The peaks of the non overlapping areas would be trap or triangle. In a car where battery is parallel I assume it looks
> pretty smooth. Not sure with the isolator how it looks on alt side.
> --
> John Lebetski
> Woodstock, IL
> 77 Eleganza II
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
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