Home › Forum › Ask A Member › Anybody test a vacuum cut-out? ’57 Lark › Re: Anybody test a vacuum cut-out? ’57 Lark
If I may add in simple terms to what the book says, it probably has been experienced by most people that have worked on the alternate firing Big Twin series motors, that if you somehow increase the RPM when there is no load on the engine, the darn thing then doesn’t want to slow back down. It is commonly called runaway. This usually happens if you simply advance the throttle too much in neutral. But it can also happen if you break a shear pin or lose a prop. Whatever, or whenever, is is a hair raising experience. The vacuum cut-out switch senses the condition and shorts out one cylinder until things return to normal. I should emphasize that the switch does absolutely nothing under normal conditions.