Choke Tang....Chokes 101!

[Macdon221]

Please tell me if I have this correct or not.

A) The Tang on the choke spring as in the posted picture (it's just an image from the net) as the choke spring heats up and the tang moves downward....it DOES NOT drag the rod down...only the choke pull off vacuum pulls the choke plate open, and from there just gravity and airflow to fully open the choke plate at the carb? When it cools the tang then pushes the rod back up to close the choke plate.

OR....

B) Is that Tang supposed to on top of the arm...between the arm and the little end from the choke rod so that as the spring heats and the tang moves down....the spring also "takes and pulls" the choke down as well. And also as in A above pushes the rod back up to close the choke plate when cooled.

Hopefully I am being clear!

Macdon221

 

[0DegreeEngineer]

Please tell me if I have this correct or not.

A) The Tang on the choke spring as in the posted picture (it's just an image from the net) as the choke spring heats up and the tang moves downward....it DOES NOT drag the rod down...only the choke pull off vacuum pulls the choke plate open, and from there just gravity and airflow to fully open the choke plate at the carb? When it cools the tang then pushes the rod back up to close the choke plate.

OR....

B) Is that Tang supposed to on top of the arm...between the arm and the little end from the choke rod so that as the spring heats and the tang moves down....the spring also "takes and pulls" the choke down as well. And also as in A above pushes the rod back up to close the choke plate when cooled.

Hopefully I am being clear!

Macdon221

View attachment 1746119

I believe B is the closest to accurate description if not attached the vacuum from the engine running/accelerating would close the choke not open it.

 

[Bird 426]

B. The choke pull off and the spring work together. When your engine starts, the pull off puts tension against the spring so that the engine can get some air. Keeps the tension on as the spring gets hot to fully open the choke blade. At least, that's how I view it.

 

[Macdon221]

So are you saying the assembly of the choke in the picture is incorrect?

 

[R/T Boy 67]

I believe the spring allows the choke to open. It is opened by the fast idle cam which has a counter weight, the choke blade being offset, and possibly by the weight of the arm in the choke well. I don't have a choke setup in front of me, but I think I am correct.

 

[Macdon221]

RT Boy....That would make sense according to the tang on the choke. "the springs tang moves down and "allows" the choke to open". It does not pull it down.

 

[turbine68rt]

On a #45 choke such as the type used on our 4429's, when heated, the coil expands and since the rod is connected to the bracket surrounding the tab it physically pulls the rod downward. When fully heated there is resistance to opposing force. You could take yours out and heat up the coil to verify this.

 

[Dragon Slayer]

turb68Rt is correct that the choke spring expands when heated. When cold and contracted it applies force on the rod to keep the choke blade closed.
The pulloff just opens the blade a set amount at start up so that your not over rich when the car starts.

The fast idle cam is weighted so that it drops out of locking out the secondary once the choke blade opens and you open the throttle via accelerator pedel.
Correction: it does apply weight on choke shaft to assist opening choke blade when spring force of the choke is removed. When choke blade is closed the rod attached to shaft and cam pulls the fast idle cam to lock out secondary shaft via the dog on the secondary shaft.

Want to see the divorced choke work borrow your wife's hair drier.

 

[Macdon221]

Dragonslayer and Turbine....

I know you guys are the experts....have a look at the pic I attached....

In the pic....the tang is "below" the bracket that is attached to the rod. When the spring heats and the tang moves downward it's not attached to the bracket...the tang moves down independently of the bracket. Is this correct?

Or should the tang on the spring be placed on top of the bracket?

I have seen it 2 ways..

 

[oldbee]

You’re kinda overthinking,but spring tension works to shut the choke plate when cold. That’s why you need the choke pulloff to open slightly when cold. Everything else is slightly weighted to want to be open(hot), cold spring tension tries to shut the choke. Hope I explained correctly.

 

[turbine68rt]

The rod is directly connected to the bracket and coil end, and is not free-floating when the coil heats and expands. In my previous post I noted that there is resistance if you try to pull the rod up when fully heated. Do you have the 45 choke assembly in your Charger?

 

[Macdon221]

Yes...the carter 45. I have both an original with all the markings and a repop with just the 45.

"The rod is directly connected to the bracket and coil end"......this is the part i am not understanding.

I will have to have a look again when I get home. Maybe I am messed up here.

It was my thinking that with the tang under the "connected rod and arm" that the spring was just free floating in the downward movement when heated...and from there just the vacuum pull off/airflow and counterweight opened it the rest of the way.

And when cooling occurred the tang was actively pushing the "connected rod and arm" up to make the choke moved to the closed position.

 

[R/T Boy 67]

You are correct in your thinking, and the picture above has it installed correctly. If you disconnect the rod from the coil to the choke, and open the throttle enough to clear the fast idle cam the choke should open by itself. If it doesn't quite, it certainly will with the engine running.

 

[toolmanmike]

Please tell me if I have this correct or not.

A) The Tang on the choke spring as in the posted picture (it's just an image from the net) as the choke spring heats up and the tang moves downward....it DOES NOT drag the rod down...only the choke pull off vacuum pulls the choke plate open, and from there just gravity and airflow to fully open the choke plate at the carb? When it cools the tang then pushes the rod back up to close the choke plate.

OR....

B) Is that Tang supposed to on top of the arm...between the arm and the little end from the choke rod so that as the spring heats and the tang moves down....the spring also "takes and pulls" the choke down as well. And also as in A above pushes the rod back up to close the choke plate when cooled.

Hopefully I am being clear!

Macdon221

View attachment 1746119

What's the question? The coil get's tighter whe it is cold and expands when it warms up. The vacuum pull off opens the choke up just a bit shortly after the engine starts to prevent flooding. As the engine warms up, the coil pictured above expands and opens the choke butterfly. The fast idle cam is turned by the choke going closed when cold and because of it's shape, it acts like a counterweight and goes off when you tap the acc. pedal. The
choke/fast idle/pull off system is actually quite simple when it is adjusted properly.

 

[turbine68rt]

Take a look at your choke assemblies when you get home, while holding it, heat it up until the rod drops all the way down, then see what happens when you try to pull it back up with the coil fully expanded.

 

[R/T Boy 67]

I think the OP knows how a bi-metal spring works. The question was, does the spring open the choke when it gets hot or does it ALLOW the choke to open and then close it when it cools off. In post number 1 the correct answer is A. The choke opens by itself when the spring allows it to and the throttle is opened slightly.

 

[turbine68rt]

The op's choke has the bracket above the coil tang. Mine has the bracket below the tang and the keyed end of the choke rod is above the tang, sandwiching it. This ensures that the rod travels with whatever position the coil is in, hot or cold. Been working perfectly that way for nearly the 40 years I've owned it.

 

[Macdon221]

ok....Yes....Turbine 68RT now we are getting to my point!

Which was is correct? Tang below the bracket and free floating, or sandwiched between the arm and the keyed end of the choke rod?

This is the answer that I have been seeking.

Every picture i see online is the tang below the arm and free floating. But I have 2 number 45 carter chokes and they are done differently.

 

[toolmanmike]

The choke rod should somehow be connected to the coil like turbine68rt described.

 

[turbine68rt]

Logically thinking, I would rather have my choke pulling open and being held open by mechanical means rather than hoping it opens by gravity, especially if there is any dirt, debris, or corrosion in the choke shaft preventing any free movement. I can honestly say I have never had any choke related issues with it set up like I described.