Electric Choke Conversion

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arunice
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Joined: Thu Jan 25, 2018 10:02 am

Electric Choke Conversion

Post by arunice » Wed Feb 14, 2018 2:27 pm

Hello all,

I just acquired a 63 hardtop tbird. Im in the process of renewing the engine componets and discovered the 2 heat tubes from the exhaust manifold are rusted and broken off. one tube goes to the air cleaner and the other to the carb choke. i have a ford 4100 4bl.

My intention is to convert it to an electric choke and know that the heat tube to the carb is deleted. However, what does one do with the heat tube that goes into the air cleaner?

I believe this tube routes hot air into the carb to aid in warming the fuel/carb in supplement to the choke being applied. If i were to put an electric choke on can i keep this tube to aid the carb warming and thusly warming the sensor in the new electric choke? i wonder how the sensor in the electric choke gets heated.

-Andy

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Karl
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Location: Brisbane, Australia

Re: Electric Choke Conversion

Post by Karl » Wed Feb 14, 2018 5:46 pm

G'day.
I don't have an electric choke but I suppose the choke is heated by electricity instead of the hot gases?

Reading your post it sounds like you think that the hot air goes into the air cleaner? if so this is wrong.
Filtered air is drawn from the air cleaner down the tube (which does not have any insulation on it) into the hot box that is part of the R/H exhaust manifold, then up a tube which has insulation on it so that it is not cooled, then into the choke housing where it heats up the spring to open up the choke.
You can purchase these choke tubes from Mac's, why not just replace yours? You may need to clean out the holes in the hot box to fit the new tubes into.
Karl.
1963 Thunderbird Hardtop

arunice
Posts: 9
Joined: Thu Jan 25, 2018 10:02 am

Re: Electric Choke Conversion

Post by arunice » Wed Feb 14, 2018 7:31 pm

you are correct in your assumption. i do/did believe hot air goes to the air cleaner. What contraption inside the exhaust manifold allows it to suck and blow? i was presuming that only air can come out of the exhaust manifold especially since the air cleaner is under vacuum.

im worried that there will just end up being some kind of other rusted obstruction in the manifold that will stop me from just replacing the parts. it looks like I'll have to drill out the busted tubes in order to attempt putting new ones in. thats why im leaning towards an electric choke.

does anyone have any experiences good or bad about running an electric choke?

tbird
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Re: Electric Choke Conversion

Post by tbird » Thu Feb 15, 2018 1:03 am

Just take off the air cleaner so you have room to drill the rusted broken tube ends out of the manifold using a hand held air or battery/corded drill with a 1/4" bit. It is quite easy to drill the tubes out they are usually only inserted about 3/8-12" into the manifold heat chamber or stove, they are not inserted into the exhaust gases at all. Insert the ends of the new tubes into the manifold and connect to the carb and air cleaner and you are finished.
Jim Mills
VTCI # 8071
VTCI 1964-66 Technical Editor
2002 Thunderbird
1965 Convertible
1962 Convertible (in progress)
1959 Ford Retractable HT
Many parts cars

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Karl
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Location: Brisbane, Australia

Re: Electric Choke Conversion

Post by Karl » Thu Feb 15, 2018 9:18 am

G'day,
There is no magical contraption that sucks and blows.

On the exhaust manifold there is a plate with a heavy gasket. This covers a series of grooves cast into the manifold.
The choke housing is attached to the carburetor body and there is a very small gasket, this seals a small passage that starts at the bottom of the venturi (I think) travels to the choke housing. On the other side of the choke housing a inverted flare nut joins a pipe (which is insulated) that travels to one side of the hot box on the manifold comes out the other hole and the pipe then travels to the air cleaner to collect filtered air.
So the low pressure air in the manifold/ bottom of the venturi draws air from the air cleaner, gets heated traveling through the hot box, travels through the choke housing which in turn heats up the choke spring which in turn bends. As this gets hotter it opens the choke.

Just remember, Ford didn't want to spend money making cars, he wanted to make money from cars. Simple and effective ways of solving a problem.

Point to remember, the flare nut that holds the tube onto the choke housing. this is very easily cross threaded. The body of the choke housing is made from di-cast and the thread damaged very easily. Make sure the pipe and nut are in line with the thread on the choke housing. Take your time in doing the nut up. If possible try the nut on the thread before you attach the pipe to the exhaust. Make sure the nut is free running that way when you do join everything up you will be able to just use your fingers until the nut bottoms out. Then use a spanner.This may take a little bending of the pipe.
It is a bit like trying to replace the hard brake line to a wheel cyl. sometimes it is easier to loosen the other end of the hard line or completely remove the other end (if possible) and then replace the line in the wheel cyl.

You are correct in assuming that there may be something blocking the hot box. If you attach the pipes or if you have a air compressor just try to blow some air through the hot box. It should just come out the other hole. If this does happen then the air will blow any rust out anyway.

Karl.
P.S. there is a thing called a heat shield that is attached to the carburetor in front of the choke housing. I used to think that it was there to stop the carburetor from heating up from the hot air from the radiator. I now think that it is there not to cool the choke housing down. to keep the choke housing hot to keep the choke open. Make sure this is attached.
1963 Thunderbird Hardtop

arunice
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Joined: Thu Jan 25, 2018 10:02 am

Re: Electric Choke Conversion

Post by arunice » Thu Feb 15, 2018 10:28 am

Karl, you're the best. Thank you for your wisdom.

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