Triumph Repair: 1977 Spitfire catalytic converter, catalytic converter, hydrocarbons

Question
Hi,
My catalytic converter gets red-hot when the car has been running for awhile.  Do I need a new converter, or is this a symptom of another problem?  Also, the car currently won't pass CA smog.  It passes in all areas except CO2, which measured at 4.9.  It smells like it is running rich.  Any advice would be greatly appreciated.  Thanks!

Answer
Normally red hot means the exhaust is too lean, but since you are reading high, CO2,  likely high hydrocarbons, too, it may mean the catalytic converter is plugged or the honeycomb broken.

Leaning out the mixture and retarding the timing should shift the emissions from hydrocarbons and CO2 to NOx, which, many years ago, weren't tested, so that was the "cheat" around the emissions.