Further, Ran good when parked is not a factor to consider. Starting from scratch regarding timing has a good goal. That is to eliminate a broken fiber gear or worse. If that is the case, you are in deep do-do. If you want spark, these suggestions, tests and procedures have to be done correctly and are important, as are the answers to questions. All we have from our house is your answers and observations and test results. It ain't easy from here.
The standard procedure is Spark, Gas, Compression. Those are the three things a motor needs to run. From under my tree to under yours.
Don't work on it with a hangover.
Be advised that backfiring when trying to start has a different set of causes than backfire while running/driving/decelerating/under load. All this crap I'm posting is to enable you to think it thru. Not trying give a know-it-all lesson. Questions will lead you to an "Oh shucks moment".
You had a question about the "starter button". The floor foot start button only makes the starter turn until you release your foot when you hear fire. The ignition switch turns on the power to coil/dizzy/points/plugs. Also coils do get hottish with power on, points closed or all your trying to start testing.
