I recently acquired a '73 Club Wagon with a 302 engine and a Motorcraft carb. It was running great until I took it on the highway for about 100 miles, going 65mph. Exiting and stopping at a stop sign, the engine died, then wouldn't start for about 20 minutes, after cooling down. Found a small coolant leak and refilled with coolant. I assume the stalling at stop was just from overheating.

On the way back home, however, the van would not hold an idle, and stuttered and stalled at every stop. If I continue to give the engine a little throttle now, it will keep running. I later realized it starts fine cold, with the choke on, but once the choke flap is completely open, it dies.

So I started taking the carb apart and noticed one of the brass air tubes (?) in the venturi assembly is cracked. Would this cause the problem? I'm not exactly sure the function of the tubes, but did clean all the holes out with a wire.

Could the engine overheating cause this crack in the brass tube? I'm not sure what would have caused the change.
Thanks for any help or thoughts!

 

Also, not sure if the carb is a 2100 or a 2150, I'll have to check.

 

I'm going to guess that that tube should not be cracked. That is an emulsion tube. It's where gas and air is mixed just before that mixture is introduced into the venturi of the carb. The crack may not be allowing enough fuel to the engine. I'm sure that the overheating did not cause this.
What may be happening is the engine is not getting enough fuel once the choke is off. With it on, which restricts the air flow into the engine, the fuel mixture is rich enough to run OK but not with it off.

Before you can be sure of what's wrong you do need to replace that part or you may need to get a whole carb as I'm not sure if that part is available by it's self.

 

Right, clearly the crack should not be there, but I just wanted to verify with anyone else who's seen this if stalling has been the result. Thought the cracked tube may be related to different issues.
Thanks jimbbski, your explanation makes sense--I'll see if I can solder that crack, then see if that helps the problem.

I also found this piece sitting on the floorboard the other day, which looks like a jet of some sort, but I can't find a picture of it in any carb repair kits or parts catalogs. Anyone know what it's from or if it would pertain to this issue?

 

That's a Schraeder valve - tire stem seal.

Not idling with the choke open is a classic vacuum leak symptom. Check for vacuum leaks on every vacuum line attached to the carb/intake, check the base gasket, check everything twice for vacuum leaks.

That cracked emulsion tube can't be helping anything, either.

 

Tire stem seal--that's the last place I would have looked, ha thanks.

I couldn't find any vacuum leaks before, but that's not to say they're not there. I'll check again, that's gotta be the issue.