Why Is This 1968 Plymouth Roadrunner Shooting Flames Out Of The Carburetor? Let's Fix It!

I wish I'd gotten footage of the time (or three) this Roadrunner tried to give me a really fast haircut. Oh well... This awesome '68 Plymouth has already been to a couple other shops, and no one has quite been able to get to the bottom of the rough running and horrible back firing problem. In fact, a previous attempt resulted in a shop throwing up their hands and saying it must be caused by incorrect cam timing, or something. Not so fast, there... Let's work through every ignition part and every system in the carburetor first. And, once again, let's learn an important lesson - assume nothing. ‪@rocketresto‬