I guess two things can happen. Plug fouling and detonation.
Plug fouling would cause the engine to run rough, particularly if two plugs in one cylinder would be affected. But I don't think that would lead to black smoke. Probably more light grey.
Detonation will physically tear the engine apart. Several things that may go wrong first (crankshaft, conrods, valve rods, you name it), virtually all will initially lead to massive quantities of oil getting into the cylinders. This will lead to black smoke, and a lot of it.
Carb heat should never be applied above something like 70% power.
BTW quick rule of the thumb:
White smoke - water (coolant) getting into the cylinders. Not likely in a lycosaurus but I once drove behind a porsche who clearly needed new head gaskets, as everybody started to put their fog lights on behind this guy.
Grey smoke - incomplete combustion for some reason
Black smoke - oil being burned for some reason. May be a gasket problem or something more serious.