Engine stumbles under acceleration

[Grits]

Update today.
I put SeaFoam in the gas filter and squirted SeaFoam in the carburetor and set mixture screws out one turn. Ran the engine long enough to get the SeaFoam in all the carburetor ports and hidden places and let set for about 1 hour. It smoked lots when engine was started. Reset timing and used the vacuum gauge to set mixture screws. Vacuum gauge worked this time. Runs lots better, but still backfires some through the carb when extreme acceleration. Ordered E3 plugs and wires. Will see if the plugs and wires help.

 

[Grits]

I read an article about timing by ear.
But first I replaced the spark plugs (E3) and plug wires. Set the timing by ear like the article suggested, reset the mixture screws with vacuum gauge. Just took it around the block ( my block is about 20 miles ) and it ran great. Cruising about 80 felt like 60.
Thanks for all the great help on this forum!!!