If you get a little white smoke and the tailpipe is white inside, that indicates a lean mixture which probably means your carburetor accelerator pump is shot.

 

If you get heavy white smoke especially when you stick your foot in it, it's probably a coolant or auto transmission fluid leak into the cylinder. Try smelling the tailpipe.

 

If it smells like tranny fluid, you've got a hole in the diaphragm of the vacuum modulator. This sucks tranny fluid through the vacuum line into the intake manifold and creates both the hesitation and the white smoke. Interestingly, an old fix for carbon in the cylinders was to pour a little tranny fluid in the carb throat. The fix is simple and cheap: Replace the modulator.

 

If it smells like radiator coolant, you could have a blown head gasket OR intake manifold gasket. These tend to be intermittent and unless you're a good mechanic, the fix is to take it to a mechanic you trust and let him troubleshoot it.

 

Hope that helps.