I have a 235 engine and i keep reading about this pointer and ball indicator, mine does not have one! whi is that?

I need help with my problem with a misfire on this engine, the engine has not been in service since 1979 and when i bought the truck i replaced all tune up parts, plugs, wires, cap, points, rotor, coil, rebuilt carb, drained gas tank, cleaned it, new fuel filter, replaced generator with alternator one wire, adjusted all rockers to .006 intake and .016 exhaust hot.

the new plugs get black soot, i will have to check carb settings. to do this tell me if i turn the 1 bbl carb screw in it will be running rich? right ( i am not sure ) also i have not driven it on the road yet and it is just idleing and reving so that could also add to t he black soot?!

i checked the points gap .016 and cant get this misfire to smooth out, i switched plugs the other day and it ran sweet smooth for about a minute then the exhaust started bobbing again ohwell
i cant figure it out for nothing
i am running some gas treatment thru it, i hope that gets rid of whatever it may be , i am thinking that i have some garbage stuck to a valve or something..

thanks for your help
jeff