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Old 06-04-2013, 02:57 PM
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How does the electric choke work?

I know current is applied to the choke coil, it gets hot and turns to open the choke linkage.

My question is where does the current originate from? Is it always on once the key is turned on (basically the coil slowly heats up until its 'fully cooked')? If this is the case how do hot starts work? I assume the coil would cool faster than the engine and you would run under full/partial choke after initial start, but also be hard to start in the first place.

Or does it actually use the temp sending unit to dictate the current engine operating temperature? What happens if your sending unit is not accurate or broken?

If it matters I am under the hood of a 1981 C10, no ODBC on this beast.

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Old 06-04-2013, 04:08 PM
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<a href="Choke Connection | Holley TV" rel="bookmark" title="Permanent Link to Choke Connection">Choke Connection</a>
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Old 06-04-2013, 04:23 PM
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Originally Posted by gearheadslife View Post
<a href="Choke Connection | Holley TV" rel="bookmark" title="Permanent Link to Choke Connection">Choke Connection</a>
OK that was a pretty good video, thanks! I am still curious though about hot starts. Seems like this could be a problem.
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Old 06-04-2013, 08:09 PM
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The power is on full time when the key is on so whenever you turn the key on but do not start right away the choke opens even though the engine is not running. The thermal mass of the system tends to keep the choke warm after the key is shut off to prevent the choke from closing while the engine is still warm.

It is not fool proof and I am sure there can be hot start issues but the carburetor should be set such that when the throttle is fully depressed it opens both the throttle and the choke (at least partially) to allow the engine to start when over choked.
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Old 06-05-2013, 03:49 AM
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Simple answer - under some hot start conditions the choke will have cooled off at a different rate than the engine and it may cause starting difficulties. However, its usually minor and only lasts for a minute or two.

Bruce
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Old 06-05-2013, 04:29 AM
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Quote:
Originally Posted by 75gmck25 View Post
Simple answer - under some hot start conditions the choke will have cooled off at a different rate than the engine and it may cause starting difficulties. However, its usually minor and only lasts for a minute or two.

Bruce
I ran into this, especially when I ran my car without a hood. The choke would cool off quicker and further. The cure is as stated above. Turn the ignition switch on for 20 to 30 seconds before you start the engine and he choke will open enough to eliminate any problems.

John L
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Old 06-05-2013, 04:35 AM
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The bimetallic coil in the choke reacts to ANY heat, not just heat from the electric element. This is no different than a hot air choke. If the engine is warm, or the air temp is high, the choke will be mostly open even with the key off. It also will reach operating temp faster with the key on.
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Old 06-05-2013, 04:47 AM
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Quote:
Originally Posted by joe_padavano View Post
The bimetallic coil in the choke reacts to ANY heat, not just heat from the electric element. This is no different than a hot air choke. If the engine is warm, or the air temp is high, the choke will be mostly open even with the key off. It also will reach operating temp faster with the key on.
This is why the problem is worse if you don't run a hood. The residual heat is not trapped around the carb under the hood.

In any case I have never found it to be a big issue.

John
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Old 06-05-2013, 08:39 AM
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Originally Posted by John long View Post
This is why the problem is worse if you don't run a hood. The residual heat is not trapped around the carb under the hood.

In any case I have never found it to be a big issue.

John
You are correct, and in reality if you don't run a hood you can tweak the adjustment on the choke coil so it opens at a lower temp.
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Old 06-05-2013, 08:58 AM
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Quote:
Originally Posted by joe_padavano View Post
You are correct, and in reality if you don't run a hood you can tweak the adjustment on the choke coil so it opens at a lower temp.
True Joe. The only issue I had at all was tweaking the fast idle so it worked well at cold start but did not idle too fast if someone ask me to crank it up at the local cruise while the engine was still warm. It was not a problem with the engine loading up or anything. It just interfered with the cool factor. Since I was not running a hood I could reach over and bump the fast idle down by hand.

John
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