I believe my 1964 \6 choke bimetallic spring is broken – Can anyone confirm?

[MDchanic]

On my newly acquired 1964 Dart, the choke spring will push the choke closed when cold, and the pull-off diaphragm appropriately cracks the choke once running, but as the engine warms up, the choke rod from the exhaust manifold to the carburetor goes slack and doesn't open the choke butterfly. If I disconnect the rod and open it with my finger, it will stay open easily.

Upon disassembly, the choke bimetallic spring has a single "hook" on the end, which rests against the rod, pushing it in the direction to close the choke when cold, but no part to grab the rod when moving in the opposite direction, so when the spring warms up, it pulls away from the rod, leaving it hanging.

Second Photo: With spring end outlined for clarity.

Is it broken? Missing a little attachment part? Anything else I should know?

And, no, I don't want to install an electric choke. Unnecessary complexity, which provides very minimal real improvement.

I'd have installed a manual choke already, but this dash has NO extra holes in it, and I don't want to be "the guy" who drilled it.

Thanks,

– Eric

 

[AJ/FormS]

no, that is the way they are made. at least the later ones.
something is just sticking

In the past, when I couldn't figure out what was sticking, I just Zip-tied a nut to the choke down-rod, which made it heavy enough to drop on it's own.

What you can try, which is where I found the stiction, is to disassemble and clean the fast-idle cam. If yours is plastic, the pivot bolt will corrode and eventually the cam will not rotate of it's own weight Just clean the screw, polish it a bit, reassemble, and try it.
Oiling it is a no-no, which will attract dirt.

 

[MDchanic]

It sure doesn't seem sticky, but it does seem it would benefit from a bit of a counterweight.

It's the original carb, as far as I can tell, has the original, correct part number on the tag, has a metal fast idle cam, and all of the pieces move completely freely. That was the first thing I checked.

Guess I'll have to do more checking.

Thanks,

– Eric

 

[MDchanic]

To All:

I've had the original question answered definitively both inside and outside this forum, so I feel it's settled.

I'm always happy to talk about things, but no need for speculation on this specific point –
As AJ said, it's not broken, and something in my carb is resisting the choke opening.

Thanks!

– Eric

 

[Killer6]

To All:

I've had the original question answered definitively both inside and outside this forum, so I feel it's settled.

I'm always happy to talk about things, but no need for speculation on this specific point –
As AJ said, it's not broken, and something in my carb is resisting the choke opening.

Thanks!

– Eric

I rebuilt the Holley 2bbl on the 2nd Owner of the private shop I worked at's Dad's '87 Dakota 3.9. Always smoked and ran like s*^t cold since it was new, for 20yrs, nobody ever did a thing about it. When I rebuilt it & was setting it up, I realized the pulloff link was slightly twisted, causing it to drag & bind the "U" hook under tension. Tweaked & set, it will start & run at -10°F, drive away no problem...I bought "Trusty Rusty" a year later off of Him..

 

[MDchanic]

The choke mechanism on this one operated smoothly, including the pull-off, so that's not the problem.

In the end, the problem was that the exhaust manifold had been replaced with one from the 1970s, which, apparently, has its choke stove pocket in a very slightly different position than the 1964 manifold, which made the choke rod the wrong length.

Using both the thick and thin carburetor base gaskets combined, instead of the single thin gasket that was on there, created enough distance for the length to be perfect.

The car still runs like crap cold, but its timing is unstable and I doubt it's had a carburetor rebuild in over half a century, so we'll see how it runs after I take the distributor apart and rebuild the carb.

Thanks,

– Eric

 

[AJ/FormS]

those choke-rods can be bent to fit, I do it all the time. And the tension can be adjusted in the same way.
Glad you got it figured out tho.

 

[MDchanic]

Sure, any linkage rod can be bent to adjust, but I try to save that as the last resort, as it's usually not fixing the cause, and once you start bending rods, you can spend a lot of time bending other rods to finally get everything the way it should be.

Adding the thicker gasket, which I should really have anyway, was the easiest solution, and lets me move on to other things, many of which don't even involve this car! ;-)

– Eric