Sulphur smell in a 1974 super beetle
My sons's super smells like Sulphur, I suspect an over volting problem, but don't know how to fix it.
Pull out the back seat bottom and check the battery, if it is overcharging there will be signs of it there, make sure the battery electrolyte level is at specs, hook up a volt meter and watch it while the engine is running it should be no higher than 14.2 volts, average is about 13.8 if it higher replace the voltage regulator. You should also have the battery checked if it has a bad cell that can also cause a smell of rotten eggs. HTH