I bought a new Brawler 600 CFM Holley Carb with an electric choke. The engine has a CRT electronic distributor, and an alternator. I don't want to piggy-back 12 volts source to the coil because someone warned against this, the coil needs 12 volts steady. So I am trying to find another 12 volt running source under the hood. Thanks for your ideas.    1/8 cavman

You don’t mention what vehicle you are working on but most of our older cars do not have ‘keyed on’ electrical hookups under the hood that will permit hooking up the electric choke without that connection being a voltage drop to whatever circuit you are tapping into.  It’s important that the electric choke not be hooked up to the ignition circuit as the newer electronic distributors do rely on having a solid 12-volt voltage supply.

Running another wire to the ignition switch or having a relay in place that is ignition switch activated are the recommended options for your electric choke.

Additional comments are always welcome.

Lorena, Texas (South of Waco)

Thank you Ted for your comprehensive reply. I forgot to mention the vehicle is a Y-Block powered 56 T-bird. I have a non stock relay under the dash. I was looking for an easier way to wire the choke. My 77 year old shoulders don't like getting under the dash. I will try to get my grandson to do it     1/8 CAVMAN

I am with Ted on using an inline fuse and a relay (off ignition switch) for the electric choke. I just went through this on my 55 Club Sedan when installing a Summit Carburetor, and I am very happy with the results.

Here is blog post and some video about it.

https://www.hotrodreverend.com/post/1955-ford-part-115-summit-carburetor-sum-m08500vs-for-the-292-y-block


Daniel Jessup

Loveland, Ohio

aka "The Hot Rod Reverend"
check out the 1955 Ford Fairlane build at www.hotrodreverend.com

What size fuse?

Go figure.  It never occurred to me that splicing into the ignition circuit to feed the elect. choke would reduce voltage to the coil, or even that I might need to include an inline fuse.  Would it matter that I would only be sending 6V to the Holley choke?  Should I go to the extra trouble of installing an ingnition-triggered relay just to keep up voltage to the coil if I still have a points distributor?  Would a 6-to-12 volt transformer also be helpful?

6 VOLTS/POS. GRD. NW INDIANA

I agree with Ted not to tap the ignition coil circuit to power the choke heater. As mentioned above, an ignition triggered relay would be the best way to go. The power for the choke heater could come from a source like the battery side of the starter relay or  some other able source.  Good question regarding 6 volts to drive the choke heater.  If you have an electric choke heater in hand, why not hook it up to 6 volts and see how well it responds?  In the early days of electric chokes, Ford used the stator lead from the alternator to power the choke heater so there was voltage only when the engine was running. The stator lead produces aprox. 5 volts and it worked very well. However, the heater element was more than likely designed for that voltage, in that case. 

64F100 57FAIRLANE500

I had forgotten them, but someone on another forum posted Holley's instructions for wiring the automatic choke. The instructions specifically state not to connect the lead to the coil:

"WARNING: Connecting the choke cap to the ignition or ignition coil could result in unacceptable choke operation, poor fuel economy, and possible engine misfiring, since the voltage delivered to the spark plugs will be severely reduced by the drain imposed by the choke cap. Suitable ignition activated 12-volt sources are most electrical relays, as well as the leads to accessories, such as windshield wipers. DO NOT connect this wire to the original equipment (O.E.) electric choke source. This may not be a 12V source."

It also says "the distributor side of the coil is not a 12-volt source. It is a 7-9 volt source after cranking."   

Interesting.  I already have a 6-to-12V transformer/inverter powering my radio, so, assuming the added choke demand doesn’t exceed it’s totaled fuse rating, and since likely the choke is not polarity specific either, that circuit would be the logical source.  Even if I should run the radio without the motor, only penalty would be the increased battery drain (?).  I’ll have to do the electrical math though.

6 VOLTS/POS. GRD. NW INDIANA

For what it's worth, I have a Quick Fuel carburetor stashed in my garage with what appears to be a typical electrically heated choke cap as installed on many new Holley carburetors. At 12.5 volts, the heater pulled about 1.5 amps then quickly tapered down to about .6 amps as the heater warmed up.  Hope this helps....................

64F100 57FAIRLANE500