cat converter getting red hot

[jmrucker]

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?

[snshddog]

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.

[jmrucker]

Originally Posted by snshddog

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.

[thepeggasus]

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.

[danielsatur]

Also check similar threads @ the bottom of yours.