Abstract: In a multi-carburetor engine system, a microswitch is provided for detecting when each of the carburetors begins the transition from the idle mode to the high speed mode in response to actuation of the vehicle's acceleration. The transition is marked by the microswitch closing which in turn causes a lamp to be lit. If each lamp associated with each carburetor does not light at substantially the same time, the carburetors are not synchronized and adjustments are required. A lockout circuit is provided for setting the period of time in which all lamps must light arbitrarily low.