Did you drive a car that had a 'choke' on it?

Question

I remember my mom driving my brothers old 58 plymouth, she would have to pull the choke to get it to start. I'm not sure how that was suppose to help so can any mechanically inclined seniors explain to me what the 'choke' did? Thanks

Answer 1

I've never had a car with a choke but all my motorcycles have had chokes on them.

Answer 2

yes many times and we still have a 50 ford tractor that has a choke -- allows more gas when starting!!!

Answer 3

Yes I did and I still do ! I am an M.G. classic car lover, and I still have three of them, a very old Midget with a soft top and two M.G.B.GT`s the `youngest` of which is a 1978 model, it is still taxed insured and in tip-top order, a great fun car and it has a choke!! ( For every day work though I run a Jeep)

Answer 4

Sure have. Most cars up til sometime in the 50's had a manual choke as opposed to the automatic chokes of later years. The choke plate in the carborator simply changed the the air flow to a heavier mixture of gas in order to get a cold engine started. A common cause of "flooding" the engine was to forget to release the choke or lack of experience with setting it properly to begin with.

Answer 5

We were stationed in Sardinia (big island off the west coast of Italy)(1973 - 1976)and bought a Fiat 500 (had a 2 cylinder, 500cc engine).  To start it, you turned on the key, pulled a lever next to the floor brake (choke), then then pulled another lever on the other side of the floor brake to start the car.  It sat 4, but I had 9 sailors in it once.  The top folds back and some were standing up sticking out of the roof!

The left cylinder sometimes fouled and I'd have to take the spark plug out to clean it.  Once we were way out in the middle of the island and stopped for lunch.  When we came out, the car wouldn't start, so I took the plug out, cleaned it and started to put it back in.  The engine had a cover around it.  The plug fell between the engine cover and the engine.  I asked for help from some locals in the restaurant.  They came out, picked up the car, turned it on its side and shook it until the plug fell on the ground.  TRUE STORY!

Just like this one:

http://www.edmunds.com/insideline/do/Med...

Answer 6

yes my 55 Chev. truck has one and the starter is on the floor next to the gas petal. It all so has a throttle control  

Answer 7

I learned to drive a 1930 something chev pickup we used to haul hay to the cows .. i sat on a oklahoma city phone book.. the choke and the clutch were very confusing but after i threw daddy out the back a few times i got the hang of it..ha..i was 8!  It was great..

Answer 8

the choke lets more gas into the carburator when it's cold so the engine does'nt stall. once the motor warms up you push the choke in.New cars do it automatically. I have a 1946 willys jeep with what is called a "manual choke", meaning you have to manually control the fuel intake when the engine is cold.

Answer 9

Well.. I personally did not drive one, but my mother did, it was an old Ford s/w... 60's -something.  The problem with it was that the choke would sometimes get stuck, and my father had to instruct her how to UN-stick it.  She carried a piece of 2x4 wood in the front with her.

One day, in the middle of town, she couldn't get the thing to start.  So out she popped from the seat with the 2x4, opened the hood, SMACKED the choke in just the right place, shut the hood, got back in, and started it right up.  What a sight that must have been!

Have a Senior Day.

Answer 10

Holy cow, I'm Only Half Evil, my driver education teacher didn't give that brilliant an explanation of the choke.  Your answer really chokes me up.

Answer 11

   Sure did,I learned to drive on a car with a choke that you pulled out manually (  all cars have chokes  even today )  was  standard shift and  no power steering.  Now That was fun!

Answer 12

All carburetors have a choke in them. What you are asking about is a manual choke.  This is a cable to the carburetor that restricts the amount of air that flows through the throat of the carburetor. This increases the amount of fuel in the cylinder. This allows easier starting of the engine. After the engine reaches operating temperature, the choke must be opened so more air is allowed into the carb.  Most small engines, lawnmowers, weedeaters, etc. have chokes in their control system that are manual operating.  

Answer 13

hi . my mom had an austen healy and she had to pull the choke every time . i was told it was to get the gas flowing through , but i maybe wrong on that . it was 40 or more years ago , lol .    take care . d.

Answer 14

Yes. '52 Chevy, '56 Ford, '57 Plymouth. Now we have automatic chokes for carburetors, fuel injection doesn't require one.

The choke closed a butterfly near the top inside of a carburetor when the engine was cold. This allowed more fuel than air. Without this, engine wouldn't start.

Answer 15

Yes, I bought a car with a manual choke about twenty or so years ago.  It was a Toyota Starlet.  A cute little car that got about 40 miles to the gallon if I remember correctly.  It was unbelievable mileage for the time.  With that kind of mileage, it wasn't very peppy.  My friends  used to refer to my choke k**b as my turbo.  If I wanted to pull away from a traffic light with relative swiftness, I would turn off the a/c and pull out the choke.  Vroom, Vroom.  I think when this car came out, it was in competition with the then Honda Civic, which many people suspected had a motorcycle engine under the hood to get great mileage.  Ha ha.  

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Answer 16

Yes, more than one. The choke cuts the amount of air into the carburetor, making a richer fuel mix to assist cold start ups.

Answer 17

I'm not a senior, but I remember my dad having one. I think it was supposed to be to let some Gas into the carburetor or something.

When the engine is first started, a very rich air/fuel mixture is required because cold fuel vaporizes slowly. The "choke" at the top of the carburetor provides the richer mixture by closing and "choking off" the carburetor’s air supply. The choking effect also creates an area of low pressure inside the throat of the carburetor that helps to pull additional fuel through the main metering circuit. At idle there isn’t enough air flowing through the venturi to pull fuel through the venturi discharge nozzle. By temporarily choking off the air supply, however, manifold vacuum rather than venturi vacuum helps to draw the extra fuel through the main metering circuit.

When the choked engine is cranked, fuel is pulled into the engine through the idle port, the transfer port and the main metering circuit. Combined with the reduced air supply, it creates the extremely rich mixture that’s needed to start a cold engine.

As soon as the engine starts, it needs air to keep running and to offset the super rich fuel mixture. The choke plate shaft is offset slightly to one side so incoming air will tend to push it open. On many older carburetors, a vacuum operated piston in the choke housing or carburetor casting was used to pull the choke plate partially open so the engine could receive sufficient air to keep running. These pistons were prone to gum up and stick, causing hard starting and stalling problems.

In most later model carburetors (but not all), the vacuum piston has been replaced with an external "choke pull-off" vacuum diaphragm. The choke pull-off is also attached to the choke linkage where it pulls the choke plate open slightly as soon as the engine starts. On some carburetors, a pair of choke pull-offs are used to give a more progressive opening. If the choke pull-off fails to work (because of a vacuum leak or ruptured diaphragm), the engine may be hard to start or stall. The amount by which the choke is pulled open can be adjusted by bending the "U-shaped" pull-off linkage. If the linkage is not properly adjusted, however, it may open the choke too far, admitting too much air causing the engine to stall.

Once the engine starts and begins to warm up, the fuel mixture is gradually leaned out until the choke is fully open. This job is performed by a temperature-sensitive bimetal spring attached to the choke plate. The bimetal spring may be located in a well in the intake manifold where it is heated by exhaust gases flowing through the crossover passage, or it may be located inside a plastic housing on the carburetor itself.

The choke housing may be heated one of three ways: by hot air siphoned up through a pipe in the exhaust manifold that then flows through the housing and enters the carburetor; by an electrically heated element inside the housing; or by engine coolant circulating through a hose attached to the housing.

Whatever the source of heat, the bimetal spring reacts by unwinding to open the choke (which may occur in as little as 45 seconds or less on an emissions controlled engine). When the engine is shut off and allowed to cool, the bimetal spring contracts, winding up tighter to pull the choke shut. But since the choke linkage is also attached to the "fast idle cam," the choke won’t close until the linkage is pumped at least once to reset the cam. On automatic chokes that use an electric heating element, a temperature sensitive contact switch may be used to break the flow of current to the heating coil when the housing is hot.

Choke Problems

When the choke is defective or not adjusted properly, it can make an engine hard to start. The engine may also stall or die after it is started.

Problems with the operation of the choke will result whenever heating is lost at the choke housing. On carburetors that draw heated air through a pipe in the exhaust manifold, rust can corrode the inside of the pipe blocking air flow. Or the pipe can simply rust off. When this happens, the bimetal spring doesn’t heat up quickly enough causing the choke to open too slowly. The result is a rich fuel condition resulting in a rough idle, excessive fuel consumption and high emissions. On carburetors that use an electric heating element, a loose wire or poor ground connection can prevent the choke from opening. The choke housing should feel hot to the touch within a minute or so after the engine is started if its heat source is working correctly.

The choke can be adjusted to alter the temperature at which it closes and opens, which also enriches or leans the starting fuel mixture. The choke is adjusted by loosening the screws that hold the choke housing and then rotating the housing. This changes the relative position of the bimetal spring inside which puts either more or less tension on the choke.

Rotating the housing to increase tension on the choke (which you can detect by holding the choke plate or watching it move) will make it close at a higher temperature and enrichen the mixture. Rotating the choke housing to decrease tension will make it close fully at a lower temperature and produce a somewhat leaner mixture. Notches are provided on some housings for reference. The vehicle manufacturer will often specify how many notches rich or lean the choke is to be adjusted.

On many late model carburetors, rivets are used instead of screws to discourage tampering with the choke housing adjustment. But this doesn’t prevent adjustments because the rivets can be drilled out. Once the adjustment is made, new rivets or screws can be installed.

The rate at which the choke opens is critical. If the choke doesn’t open quickly enough, especially during warm weather, the mixture becomes too rich and increases carbon monoxide emissions. On the other hand, if the choke comes off too quickly, especially during cold weather, the mixture can lean out causing the engine to stall or to stumble when the throttle is opened quickly.

The choke pull-off plays an important role here by modifying the rate at which the choke opens during warm weather. Some carburetors are equipped with two choke pull-offs. The combination of two choke pull-offs provides a progressive rate of opening that changes according to temperature. The primary pull-off opens the choke a bit when the engine starts to keep it running. The second choke pull-off operates through a thermal vacuum switch that senses the temperature of the heated air entering the carburetor.

During cold weather, the bimetal spring in the choke housing will open the choke fully before the second choke pull-off has any effect because the choke housing warms up faster than the air entering the carburetor. So during cold weather, the second choke pull-off has no effect. But during warm weather, the air entering the carburetor is already warm. This causes the thermal vacuum valve to open, passing vacuum to the second choke pull-off which pulls the choke open sooner than it would open otherwise. A vacuum delay valve is often used in the secondary choke pull-off vacuum line to delay full choke opening for 8 to 20 seconds (to give the engine a little more time to warm up).

Answer 18

No, but my motorcycle did...