Abstract: A detent mechanism including a stop pin and a specially configured detent spring provides a recognizable interruption to an operator rotating a control shaft of an engine governor. Increased torque is required to be applied to the shaft to override the detent spring to permit further rotation of the shaft. The detent stop pin is mounted for rotation about the shaft to allow radial positioning of the pin relative to the shaft by a resiliently biased means. The C-shaped detent spring is readily replaceable to provide different tensions for different operating conditions. Fixed stopped means and adjustable stop means limit rotation of the shaft with the detent mechanism operably positioned between the two stops.