cat converter getting red hot

1977 mgb, I started it for the first time this year and it seemed to be chugging and blowing black smoke out the tail pipe. I checked under the hood and the cat converter was cherry . so i shut it off right away. any ideas of what it could be? i'm guessing a plugged converter?

I would check for a cylinder that is not firing. That would push unburnt fuel into the exhaust which would explain black smoke and a overheating cat. A plugged cat should not make the black smoke. Could be a stuck float in the carb causing overfueling. There other possabilities but I would start there.

I would check for a cylinder that is not firing. That would push unburnt fuel into the exhaust which would explain black smoke and a overheating cat. A plugged cat should not make the black smoke. Could be a stuck float in the carb causing overfueling. There other possabilities but I would start there. thanks for the help i'll start there, it just might be the carb i have never rebuilt it and it has sat a long time i ran it last year when i started to work on it but it sat all winter thanks again.

Another possibility are the screws securing the automatic choke assembly to the carburetor. They can back out over time thus allowing the mixture to richen. This can also cause a fuel leak leading to a fire so this should be checked in any case.

Also check similar threads @ the bottom of yours.