Oh I don't know Bill - there be beasts that need something to stop the entire contents of the tank heading straight for the crankcase! Nortons, AMC twins (my weakness), etc. A mag earth diverted to a tap works fine as long as sod's law doesn't intervene. I'm inured to the problems and have several inline feed taps. Despite warnings of the perils, so far so good . . . fingers crossed . . .. It's all a question of doing the pre-flight checks . . . fuel on, oil on, ignition cut-out off, FIRE! Keep looking for non-existent taps on my BSAs (good discipline!) . . . and I find them not . . .
But boy, are the consequences of early Alzheimer's dire . . .