Odd Vacuum Setup on MC2100

[007]

Can anyone explain what this is and what I need to do to fix mine since it's broke? Notice the difference in the next two pictures.

Here's a little better view of how it's plumbed up in the back of the choke mechanism.

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[DHugg]

That's the heat riser that gets hot air sucked past the choke bi-metallic spring. When the spring heats up, it pulls off the choke as the engine heat advances. Just like the one on my '80 CJ7 AMC 304 AMC.

I'd personally prefer a manual choke and listen by engine sound when to ease the choke off. But that's what I had on my first car, a 1941 Plymouth. Works good; lasts a long time; cleans with a damp cloth; polishes to a high gloss!

 

[007]

Okay well mine is broke there on the right, flush with the plate on the intake. Is this an Autozone part or a junkyard part?


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[007]

I'm confused as to how this could be something that moves heat? It's going right in the intake manifold?

 

[Petescj]

I'm confused as to how this could be something that moves heat? It's going right in the intake manifold?

They break quite frequently and I cannot remember there being a replacement part for it. Its a heat riser like stated and actuates your electric choke.

 

[007]

They break quite frequently and I cannot remember there being a replacement part for it. Its a heat riser like stated and actuates your electric choke.

Well that's another reason for a manual choke. I'll take that top plate off and fill in the holes or make a blank and just go to a manual choke. I prefer them anyway.

Thank you both...

 

[IOPort51]

It more than likely works pretty well just the way it is. Look at the throttle plate when it is cold and see how well it opens when it is warm. I, personally, think automatic chokes are a terrific thing, one more thing I don't have to remember.

The manifold vacuum pulls warm air past the choke spring which then expands to open the choke. The heat coming off the engine is enough to open the choke. I do not think I have that tube still on my choke and the vacuum line is plugged, the choke still opens when it gets warm.

 

[007]

It more than likely works pretty well just the way it is. Look at the throttle plate when it is cold and see how well it opens when it is warm. I, personally, think automatic chokes are a terrific thing, one more thing I don't have to remember.

The manifold vacuum pulls warm air past the choke spring which then expands to open the choke. The heat coming off the engine is enough to open the choke. I do not think I have that tube still on my choke and the vacuum line is plugged, the choke still opens when it gets warm.

The one with the vacuum line is fine, it's the other one that's broke - the one that goes in the choke mechanism...

 

[IOPort51]

Now I see your point. Do you have a picture of where the vacuum line is connected to the manifold?

You would think it would need a positive pressure to put warm air in the choke spring. This will require a bit more research.

 

[007]

Now I see your point. Do you have a picture of where the vacuum line is connected to the manifold?

You would think it would need a positive pressure to put warm air in the choke spring. This will require a bit more research.

Here's the whole setup... The red circle is where the break is.

 

[IOPort51]

Here's the whole setup... The red circle is where the break is.

I understand and see where the brake is. The tube is all one path, if the end were still connected to the plate. The rubber hose does not connect to the manifold, it connected to the hat box or the plate above the level of the choke plate.

Warm air rises into the choke disk and the other end allows clean air to be drawn into the tube before it goes into the choke disk.

all that is needed is for the bell shaped weight to get warm and allow warm air to rise into the choke spring. The rest of it is just to supply clean air so the choke does not get full of dirt/mud/whatever.

If your choke is not opening I would look to the adjustment of the spring but I am thinking you have a working automatic choke as it is.

 

[007]

Gotcha, well I was just rooting around in there trying to get a handle on how much vacuum line I needed to replace ALL vacuum lines on this thing doing it one at a time and capping off what's not on a line. I just barely touched this thing and it spun sideways and the break is flush with the plate. I guess if the choke works I could remove the plate and put a fitting in there and reconnect with a fuel line or solder it. I'll try to salvage what I have before chucking it for a manual choke.

 

[IOPort51]

If it were mine, I would ignore it. It works and I bet the way it got broke was some one removing the carb without removing the tube nut. If the pieces look like they could fall off and get wedged in the wrong place or do damage in some other way I would give it more thought but I don't see that happening.