You guys are great! Pictures posted before I could respond!!! Wow. JimsRebel, thanks for the pics, helps a lot! Gives me a clue of where to look for the fresh air input to the choke hot air circuit. I see you must have a little later model based on the presence of the oxygen sensor than my 1980 F150 which doesn't have a computer or oxygen sensor or feedback carburetor. I'm headed out to the shop to take a look. Won't surprise me to find out that one of the "many" previous owners may have removed or disabled this plumbing.

 

I took a look at the underside of the exhaust manifold. There is a nub there with a small hole where the plumbing is supposed to be.


I'll have to figure out a way to get some steel tubing connected to this?

 

The hard part will be cleaning out the holes first. There is about .25 inches of the old pipe still in there. Here is a photo showing a good tube next to a bad tube.
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JimsRebel your pics are worth a 1000 words and much better than mine with the wrong camera date!! Where did you manage to find good parts in such good shape for replacements? Digging the rusted off dutchmen out of the cast iron manifold isn't going to be easy. I'm not sure that with my feeble eyesight and advanced age it's worth the energy? I sure as heck am not going to pull the manifold just for this. Maybe if I have it off for some other purpose I'll attack the dutchmen. Perhaps I should start thinking about the soft copper wrapped around the exhaust manifold. Ain't going to be pretty or elegant but it might work....

 

That is why I posted the pictures, as I see this as almost impossible to do.

In all my many junk yard trips, I only found 1 set of pre-84 tubes that where still usable... after I removed them.

Jim

 

I've been to the two closest salvage yards to me and there must be at least 60- 70 Ford six cylinder vehicles of the appropriate era and not a carburetor or exhaust manifold in the bunch. Tells me they are practically impossible to find and the more obscure parts like your vacuum lines impossible. The soft copper line is looking better and better?

Carburetors are a vanishing thing! A few years ago I sold a YFA core on the Denver CL. Wish I had kept it for parts but at the time didn't have anything that could use it. I should have suspected it was a rare commodity when a company in TX contacted me about buying the carb. They sent me a prepaid box and paid my $75 asking price plus paid me a little extra for packing it up and sending it to them!

 

This is the idea on how the choke stove was originally setup:



A thermostatic "hot air" choke in conjunction with an electric assist is what Ford used on the stock Carter 1V carburetor and Motorcraft 2V carburetor. The way it works is this:

Clean, filtered air from the air cleaner is pulled through the "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 air gets hot, it closes the spring in the choke cap, which allows the choke plate to open up as the engine warms up to run on a leaner mixture.

If your original choke tubes have rusted off, you are going to have to remove the exhaust manifold from the engine and drill out the broken tube(s). OR, you can purchase a universal Choke Stove Kit (Dorman 03840) found in the Help! section of most auto parts stores. This simple, cheap kit (about $20) is designed to bypass the choke stove chamber on the exhaust manifold and replace the stock choke tubes completely. The kit comes with a length of coiled up aluminum tubing that you can easily bend by hand, the tubing insulation, the hardware to mount the tube to the choke cap, and a little "dome" with a hole in one end for the tubing to push into. This dome clamps to the exhaust manifold or header pipe to trap the hot air when the engine is running and routes the hot air up to the choke cap:

Here is a picture of the universal Choke Stove Kit on my own truck. I have a V8 engine, but the concept is still the same:



The factory setup had a "fresh air" tube that routed from the carburetor air horn down to the bottom of the choke stove chamber on the exhaust manifold. This location provided filtered air because this area is located on the "filtered air" side of the air filter once the air cleaner is in place. Since it is not absolutely necessary, the hot air choke kits don't use the fresh air tube at all. I improvised and drilled a second hole on the other end of the dome that came in the Choke Stove Kit so that the hot air going into the choke cap would be filtered, more like how it originally was set up in the first picture. You can see where mine attaches to the carburetor air horn by the rubber hose right behind the choke cap.

The "electric assist" portion of the stock choke system does not work on its own like an aftermarket electric choke. In fact, it doesn't have to work at all in order for the hot air choke to be effective. It is only there to "assist" the hot air choke in temperatures above 60 degrees, where it helps the choke come off sooner for cleaner emissions. It doesn't work at all when the weather is colder than 60 degrees. It connects from the choke cap by a wire that connects to the back of the alternator. Ford knew what they were doing by connecting it here, because the electric choke would only be energized when the engine was actually running. This part of the choke is secondary, meaning the choke will work without it, but the choke will not work without the thermostatic "hot air" choke system.

The stock thermostatic "hot air" chokes with electric assist works MUCH BETTER than the fully electric chokes found on all aftermarket carburetors in that the choke opening corresponds with the engine temperature. As a result, the engine gets the right amount of choke it needs, and because it uses hot air generated from the engine, it doesn't choke the engine when it isn't needed. Fully electric aftermarket chokes rely on a timer that reset every time the engine is turned off, so they don't work nearly as efficient.

 

First off, the gold bracket around your choke looks like the same thing I have seen with a heater hose stuffed in it as the sole heat source to warm up the choke on older Ford sixes. Not sure how well this worked but it is quick and easy looking. It would seem like you have to have the heater on to get water circulation through the hoses.

I just test my original stock carb choke.
75 deg ambient temp. The choke current draw was .5 amps, heated up and the choke pulled within a minute or so.
I had 2 other loose choke caps off of Ford sixes that also had higher current draw, over 1 amp at this temp. I then put them out side in the sun (95 deg) and the current draw was the same.

On every Ford electric choke I have tested they pulled just fine on "electric alone mode". I have only tested 4-5 in line six Carbs at room temp.

I put all of this stuff in the frig and will do another test later and I will watch the time closer next test.

Testing was done at 8 VDC using a regulated power supply.

Jim

 

After 1 hour in the frig the stock motorcraft carb choke cap did not work, no current draw.

But one of the 2 loose ones was a shinny new replacement part, it worked just the same as before.

So if you are unable or unwilling to fix the hot air choke system, you still have the option of using a choke cap that heats in both a hot and cold environments.

Thanks and Reps to Lariat 85 for posting this info. I learned something new about my truck today

Jim

Sorry, I couldn't Rep you "again"... I need to spread the love around.............

 

LARIAT 85, that is some very useful info! I had no idea tha Dorman had a kit to address the problem I'm having. Your info about the function of the hot air vs. the assist of the electric choke thermostat is the most enlightening I have never read. It has clearly explained the functionality about the thermo/electric choke that Ford designed into their vehicles.

The cleanliness of your engine bay is immaculate!!!!!!!!!! I'm envious.

Thanks for the info. I'm going to give it a shot. Finding a place to wrap the aluminum tube on an inline six won't be anywhere as near sanitary as on your tube headers but I get the idea. I'm just trying to get this old beater Ford ready for trouble free winter starting and thanks to your explicitly clear description I think there is hope.

Thanks for taking the time to respond and special thanks for providing the source part numbers from Dorman. This forum rocks.

 

Wow, had I known or been more creative in using the correct search terms the answer was here all along, dang!

https://www.ford-trucks.com/forums/1...fold-tube.html

Seems HIO Silver posted in the above link with the same reference to the hot air repair kit. Search terms are important. I guess creative search terms are even more important. I think I am google impaired or more conditioned to search like in the pic?

Just got this pic from a friend. I think it applys?

 

You know, I am sure you could stare at this situation for awhile and come up with something that would work. I don't see why you could not bend a piece of copper to just lay right against the exhaust manifold for a few inches to warm the air flowing through the copper tube. You could use large hose clamps to hold it against the manifold, or if you happen to have some tapped holes you could use, you could make some metal clamps that would look nicer.

Same with the heat stove for the aircleaner pipe. I have made several of them using aluminum flashing from the lumber store. You would be surprised how primitive and simple it can be and still draw enough heat from the manifold to do the job.

 

My wife and I agree - that pic was taken in the late 60's judging by her hair, head band, and sweater. Do we remember the late 60's? Sure do - we got married in '69. (And our DD was a '69 Bee.)

 

Quote:

Originally Posted by JimsRebel

First off, the gold bracket around your choke looks like the same thing I have seen with a heater hose stuffed in it as the sole heat source to warm up the choke on older Ford sixes. Not sure how well this worked but it is quick and easy looking. It would seem like you have to have the heater on to get water circulation through the hoses.

That bracket on the side of it is indeed there for a heater hose to rest against. This is how Ford did it in the mid to late 1960s. The idea here was the same as the later "electric assist" choke caps that were introduced in the mid 1970s and used until electronic fuel injection took over. The heat from the hot water in the heater hose from a warmed up engine will open the choke quicker and keep the choke open longer so that the engine doesn't get choked unnecessarily.

The carburetor I am using is a Ford Autolite 4100 from the mid to late 1960s. It is essentially the same as the stock Motorcraft 2150 my truck originally came with except it has two extra barrels. As you can see, the Autolite 4100 also used the thermostatic hot air system to open the choke. (I have since added an electric assist choke cap, and my truck drives every bit as good as any modern engine equipped with EFI.) In fact, that is precisely one of the main reasons why I chose that carburetor. I used a Holley Street Avenger for a while that worked okay, but the driveability wasn't near as good as a stock Ford carburetor and the fully electric choke didn't work nearly as well as Ford's system.

The all-electric chokes found on aftermarket carburetors work on a timer, so the choke will reset every time the engine is turned off. Also, these chokes uses a keyed 12 volt power source, so if the engine is off and you turn the key to "RUN", the choke will energize and unnecessarily run its normal cycle, which means the choke won't turn on when you start the engine from there. In contrast, Ford's electric assist choke caps use 8 volts and connect to the back of the alternator, which means it will only energize when the temperature is above 60 degrees and the engine is actually running.

Capiche?

 

Well, since aftermarket carbs were by definition add-ons the 12v source for the power can come from anywhere. Mine comes from a relay pulled in by the stator terminal on the alternator, so the choke doesn't get voltage except when the engine is running.

And, my Edelbrock carbs don't have a timer on the e-choke - they heat all the time the engine is running. And, without a timer it doesn't reset when the key is turned off. It works adequately. But, I do agree that the hot-air choke is better.