Seen this before, what a scary few minutes, engine would not restart, all the valves were
super tight another few seconds and boom! The mechanic was changing the vacuum
pot for shut down and missed. The large shop was shaking and filled with black smoke.
Every one was ducking behind cars. I was able to spin off the fuel filter, the engine
slowly came to a stop. Poor Guy he was shaking, I told him to seat down, I adjusted
the valves ,all the adjustment nuts had come loose and almost off!! All was OK.