Back fire, no power

[27TV8]

Took my car out for a drive today. It ran fine till it warmed up then it lost power and as I gave it gas it backfired out the exhaust. No intake backfire but it seems to be running extra rich? The carb is a 48.
Any chance the fuel of today is effecting it? I do not drive it much but always turn the fuel off and let it die when I plan on leaving it for awhile.
I just made it home and expect if I had further to go It would not have made it!
Thanks
Thomas

 

[Tinker]

Stuck valves from sitting? Maybe a bit of driving and a drizzle of mmo?

or bad coil/condenser due to heat maybe?

 

[JWL]

My first guess is defective condenser.

 

[APDAVE]

Maybe bad coil ,my car gave me fits with bad coil or as JWL said Bad Condenser! Dave