A reliable electric choke
 

Back in the day, I used to adjust my auto choke vehicles with the seasons,(both my mother and my wife liked auto chokes in their cars). There are no electronics to tell the carb what the environment is like, so you have to tune it accordingly. That being said, on ALL of my own vehicles, from the '60's to today, I converted to manual choke. They never fail, your brain is the electronics that adjusts them with the seasons.:-X0A6

How isn't it functioning correctly? All it needs to do is close when it's cold and open at a rate that matches engine warm up. If you live where it's consistently below about 20 in the winter, it may need to be adjusted to close more/ stay closed longer during those months. Once you figure out summer/ winter settings, mark the carb, you shouldn't ever have to touch it. I think it's possible to get different springs for them also for faster/ slower opening.

It's be nice, but expensive, if someone made a kit that replaced the spring with a small stepper motor and controller that moved the choke based off air/ coolant temp.

They do, it's called Fuel Injection:-drink

Lol I shared the same frustration but let me add some wisdom based on my another carb or efi saga. If you have an engine that doesn't produce enough vacuum then Throttle Body EFI will not work well because it will not sense load. I went through two electric chokes on my Quickfuel carb that less then two years old and battled the same frustrations. However, mine were double pumpers I am going to try a vacuum secondary and maybe get a wide band o2 guage to see if i can tune a carb as good as efi.

The electric choke isn't the best setup even when functioning as intended. It is sensitive to temps and start up procedure. The factory automatic choke setup worked better though more complicated.

EFI works well for me on a hot rod. I will add it to my dent someday. I do believe a warm camm'ed engine can run throttle body... just needs to be a higher end system that is user tunable. And will need some tuning.

Tuned correctly and with the right selection of parts, there is very little difference between a vehicle with a carburetor compared to one with electronic fuel injection. That being said, there are three things that a carbureted vehicle needs in order to run as good as a fuel-injected one:

1. - A thermostatic air cleaner on top of the carburetor.
A thermostatic air cleaner is an item a carbureted vehicle (and throttle-body fuel injection) needs in order to match the driveability of a modern vehicle with EFI. This style of air cleaner is what Ford used on their carburetors from the 1970s until they went exclusively to electronic fuel injection. These provide warm air for a cold engine, and cooler outside air for a warm engine. Not only does this prevent carburetor icing and functions as a true "cold air" intake, it also mixes between the two sources to help keep the incoming air going into the carburetor at a consistent temperature. In turn, this maintains a more consistent air/fuel mixture all year round, which means seasonal carburetor choke adjustments and/or jet changes are eliminated.

The problem with an open-element style air cleaner is that it feeds the carburetor underhood air all the time. This means that the air going into the carburetor is too hot in the Summer and too cold in the Winter. Hot underhood air in the Summer hurts performance and efficiency, while cold air in the Winter hurts driveability and efficiency. Because of the wildly varying air/fuel mixture from the different temperatures, you would need to make seasonal choke adjustments and/or jet changes for optimum performance and efficiency.


2. - A carburetor with a thermostatic choke.
Aftermarket carburetors use fully-electric chokes because they are cheaper to produce. They often come off too fast, and will sometimes choke the engine when it isn't necessary. The problem is that they run off a timer. After a certain amount of time, they turn off, no matter what. Then, they will sometimes turn on again and choke the engine when you don't need it - such as re-starting a warm engine after stopping at the store. Even worse, sometimes they will turn on and run through it's cycle when you are sitting in the car listening to your radio. Then, when you start your engine, the choke doesn't work. :(

If you would like a properly functioning choke, you need to find a carburetor with a thermostatic choke. Many production vehicles with a carburetor from the 1960s until they switched to EFI used this style of automatic choke. The early Autolite 2100/4100 carburetors used a thermostatic choke, and the later Motorcraft 2150 used a thermostatic choke with "electric assist." A thermostatic choke works MUCH BETTER than the fully electric chokes found on aftermarket carburetors in that the choke opening works in lock-step with the engine temperature. As a result, the engine gets the right amount of choke it needs. And because it uses heat generated from the engine, it doesn't choke the engine when it isn't needed.

The way the thermostatic (hot air) choke system works is this:
Clean, filtered air from the air cleaner is pulled through a "fresh air" tube (a rubber hose that is connected to the carburetor air horn and attaches to an aluminum tube) and into the bottom of the choke stove chamber on the exhaust manifold, where the air is heated up when the engine is running. From there, the heated air goes back up through the insulated "hot air" tube (attached on the top of the choke stove chamber on the exhaust manifold) that connects to the choke cap. As the engine warms up and the air gets hot, it relaxes the spring in the choke cap, which allows the choke plate to gradually open up as the engine warms up to run on a leaner mixture. (Some models use coolant temperature to accomplish the same thing.)

The "electric assist" portion of the stock choke system found on the later Motorcraft 2150 carburetor does not work on its own like an aftermarket electric choke. It is only there to "assist" the thermostatic choke in temperatures above 60 degrees, where it helps the choke come off sooner. It connects from the choke cap by a wire that connects to the back of the alternator. As a result, the electric assist will only turn on when the engine is running. This part of the choke is secondary, meaning it simply assists the thermostatic choke system. Earlier carburetors without the electric assist placed a heater hose up against the choke cap to serve the same purpose.

When you have a thermostatic choke and a thermostatic air cleaner set up correctly, your truck should start right up on even the coldest day - and continue running without stalling or hesitating. And, you should be able to put the vehicle in gear and drive away within seconds, just like a vehicle with EFI. The *only* difference between the two is that you have to remember to push the accelerator pedal to the floor to set the choke on a carburetor. Anything less than these results means something is not right.


3. - A carburetor with annular discharge boosters.
No other design atomizes fuel as good as Ford's annular discharge boosters. Annular discharge boosters atomizes fuel almost as good as fuel injection. (Holley purchased the rights to use this design when Ford went exclusively to EFI. In fact, the better aftermarket throttle-body EFI systems use annular boosters!) The stock Ford Autolite 2100/4100 and the later Motorcraft 2150 carburetors have these. The Summit Racing carburetor and some Holleys also have them, but these carburetors use an electric choke.


When your truck was new, it came with ALL of these items. Just like EFI systems, it makes a difference when the necessary items are in place and functioning correctly. Properly adjusted and with all necessary items in place, there is very little difference in driveability between a carbureted vehicle and one with EFI. And that includes cold starts and cold weather performance.


A Ford thermostatic automatic choke works even better if it is set correctly. :)

Fully electric automatic chokes do *not* work as well. :(

Agree with Ericj, I have converted most of my edelbrocks and 2150's to manual chokes, and no more wondering what position the choke is in. the cable knob acts as a rudimentary gauge telling you full on or full off, or to what degree in between. No more adjusting, plus no more brapping (brap! brap! brap!) the gas pedal trying to force the high idle down early when you don't want high idle, (such as during quick troubleshoosting, or when loud exhaust noise is unacceptable). The conversion kits are only about 12 bucks too.

On the contrary, the user has to *constantly* adjust a manual choke anytime it is being used. That is why it is called a "MANUAL" choke. :rolleyes:

Electric chokes and thermostatic chokes are both AUTOMATIC chokes. Once they are set, they work automatically. :)

You should not have to "force" the high idle down early on an automatic choke. If the high idle won't drop down to the second step after 10 seconds or so, that means your choke is set too tight. Or, it could be REALLY cold and the engine needs a few more seconds to idle on the higher step before it is ready to drop to the second step and run on the leaner fuel mixture. Even vehicles with EFI will have a higher idle when a colder engine is started. And, like a modern EFI vehicle, you should be able to drive away immediately, even if the high idle is on. Unlike a manual choke, an automatic choke will gradually open automatically as you drive. And when the engine is warm enough, the choke will completely disengage and the engine will automatically revert back to curb idle.

Capiche?

Choke
 

So what do you suggest for those of us with aftermarket intakes and carbs? I guess I'd rather have an electric choke than no choke at all, or a manual choke. I learned a lot from your posts about how the choke stove system worked. I'm not sure mine was ever functioning as intended.

Does anybody make an aftermarket thermostatic? I've always been in the same boat in northern MT, can't keep an electric in it's "sweet spot" - don't know why, yearly temps here only vary from -40 to 110. :)

You can help an electric out quite a bit by triggering it off an oil pressure switch, so it's only powered when the engine is running - that'll get you away from it starting to open while you're cranking, or if you have the key on for other reasons with the engine off. I've also found that you can insulate the carb "too good", in cold weather with a phenolic spacer the choke just seems to stay on partly, even though they're electric, engine/carb body heat will also help pull it off. Same thing with hot air stoves off the manifold, at least up here you ABSOLUTELY need to keep your factory air cleaner housing and the associated vacuum plumbing to make them work better.....

My driver pickup still has the stock carb with the stock auto choke, and that's the main reason I haven't done much to that motor - it starts and runs too good to want to screw that up. :)