immortal1 (linn)
+1y
Combination of rich idle mixture and higher than needed idle speed. Many older carbed vehicles had a small solenoid for an idle speed stop/adjustment - when the ignition was turned off, the solenoid collapsed and effectively closed the throttle plates. Engine stopped every time.
Not all carbs / engines need them but my guess, in your case is a lower idle speed and slightly leaner mixture will solve your problem.