CBGSTYLES

Carter carburetor choke problem

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HELP

I have a 1964 impala with a Carter carburetor 4 bbl .

The  choke does not close. 

I took the automatic choke apart, and seems like the spring is only supposed to operate in the open direction,  as it heats up and uncoils .

what closes the coil ? 
 

this is a pic of the spring I have
 

BC4997D2-DC3A-4B2F-95AE-15A8E71C169F.png

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Not sure but I think that on my'68 AMX with a four barrel Carter the Spring Plastic Housing can be rotated to dial in the sweet spot to make the choke work at some point. Also, most chokes will go to the choke position it you press the Gas peddle down and then release it before cranking the engine. Hope this helps.

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It was a common problem that those coil bimetallic chokes springs in the plastic housing carb mounted and the manifold mounted choke stoves. As they aged, all that flexing would make them lose some of their ability to travel for the full range needed to operate the choke plate. First sign of that is the first really cold day of late fall they wouldn't close enough to start the car. So some would turn the plastic housing to the point of making them be able to close again.

 

That would work for awhile until they lost too much travel.  If you adjust them further to be able to close then the wouldn't open fully and the carb would run rich. Had to replace quite a few back in those days. 

 

Paul

Edited by PFitz (see edit history)

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The bimetallic coil CLOSES the choke butterfly. The choke butterfly is opened by the internal choke pull-off (a.k.a. vacuum piston).

 

Different chokes opened/closed in the opposite direction. Perhaps some previous owner bought a cheap choke with the coil expanding wrong for your application. Generally, the coil may be removed and reinstalled in the opposite direction.

 

Automatic chokes

 

Jon.

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Hi carbking

it’s a 1964 Carter model ?what do you mean the 

bimetallic coil ?

 

its the original choke and right according to the books 

the only way I can see that the

way my works is that the spring will open the choke as it expands 

Edited by CBGSTYLES (see edit history)

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Bimetallics are two metals one over another causing heat to bend them to a point where it causes another device open or close if I recall.

One other thought with your set, up does it have a heat riser tube coming off the exhaust manifold to the carb?  

Edited by Doug Novak
Clearfication (see edit history)

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Hi Doug 

yes it does have a heat tube I posted pic of the one I have 

any help would be great 

the only way mine works is the 

spring expands opening the choke 

but once it cools and retracts 

the choke stays open 

what’s closes it?

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That choke coil is bimetallic. IIRC. That is how it moves in response to heat. 
 

Yes the coil Closes the choke plate. As it heats up, it stops holding the choke closed. But does not open it (on this model, some have a bimetallic coil with a circle end that can open the choke). The Choke pull off is always trying to open the choke. Usually this choke pull off is the piston inside the Carter choke housing. 
 

Frank DuVal

Edited by Frank DuVal
Spell correct issue. (see edit history)

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From the link I posted earlier:

 

Operation – integral hot air chokes

The integral choke, like the divorced choke, closes due to a coiled bimetallic strip that rotates with temperature change. The coil is located inside the integral choke housing. Also inside the choke housing is a vacuum piston assembly. An internal vacuum source enters the choke housing behind the vacuum piston, and escapes by the choke piston to cause a negative pressure (vacuum) on the entire integral choke housing. As the housing is connected to the hot air choke tube, this negative pressure pulls air heated by the exhaust through the heat tube. This hot air causes the tension of the coil to relax, allowing the vacuum piston (this may be thought of as an internal choke pulloff) to open the choke plate.

 

Adjustment – all except electric chokes and the 1937-38 Delco unit

All chokes other than the above may be adjusted as follows: pick a time with the ambient temperature is between 65 and 70 degrees F. (68 degrees F. is the perfect temperature), and adjust the choke such that the choke plate on a cold engine just TOUCHES closed, with zero tension. The choke coil will then compensate for other temperatures

 

If the above doesn't explain the operation to you - 573-392-7378 (9-12, 1-4 Mon-Tues central time).

 

Jon.

Edited by carbking (see edit history)
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One other thought just occurred to me:

 

Lincoln once used a choke coil that uncoiled exactly opposite from those used by other companies.

 

Possibly some well-meaning unknowing vendor sent one of these "across the sea" and had it reproduced to sell for other makes; or possibly the company doing the reproductions did not understand the function of the part.

 

Jon.

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9 minutes ago, CBGSTYLES said:

Hi Doug 

yes it does have a heat tube I posted pic of the one I have 

any help would be great 

the only way mine works is the 

spring expands opening the choke 

but once it cools and retracts 

the choke stays open 

what’s closes it?

 What closes the choke is the spring having enough tension to reach full travel .

 

As I said,  they age, and after a lot of flexing in a hot environment they start to lose some of their tension. Then they don't travel far enough to close fully in cold weather. I've had to replace many back in the 60-80's because they would not close without over adjusting, thus causing a problem at the other end of the operating range. They only other reason they don't close is if the choke plate and linkage are hanging up from crud or corrosion, or someone bent the linkage.

 

Paul 

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I have seen many owners throw away those pesky things and replace them with mechanical wire pull  chokes . Those kits were sold at many  outlets. I saw one such choke with a steel tube from the exhaust manifold to the spring assembly all blocked with exhaust goosh. That was one of them condemned and replaced with the manual kit.

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That should be a Carter AFB (aluminum four barrel). I have seen two types of choke used by GM cars, one on the carb that is adjusted by loosening the three screw and rotating as mentioned. The other bolts in a stamped housing to the intake manifold by the crossover (is this for a QJ ?). This one adjusts by bending the rod to the carb.

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