How To Fix Off-Idle Stumble - Idle Talk

Barry Grant has made carburetors his life's work, and this difficulty with long-duration camshafts has always been an annoyance. So Grant came up with an elegant solution he calls the Idle-Eze system. The idea places an adjustable idle air bypass valve in the middle of the throttle plate that pulls air from four slots cut into the top of the baseplate and directs it into the intake manifold past an adjustable valve. To modify an existing carburetor, all you have to do is disassemble the main body and baseplate and drill a hole through the carb stud hole, and you're ready to reassemble the carb. Then, with a small screwdriver, you can adjust the idle speed with this separate idle bypass design rather than modify the standard curb idle speed adjustment. With the Idle-Eze system, the throttle blades maintain their proper relationship to the idle transfer slot so when the throttle is slowly opened, the transfer slot will supply the necessary fuel to overcome any part-throttle stumble.

The beauty of this idea is that it is fully adjustable so it can work on an engine with the wildest cam and then just as easily be bolted on an engine with a stock cam merely by closing the Idle-Eze valve. For now, Grant has adapted the Idle-Eze idea on new throttle plates available for most of the larger Demon carburetors. Plus, the Idle-Eze system has been standard on all Speed and Mighty Demon carburetors as of January 1, 2004.

Regardless of how you approach the repair of this problem, the key is the proper relationship of the throttle blades to the idle transition slot. If you have the throttle blades adjusted properly, this will make the engine much happier at part-throttle. And nobody wants to look silly when the engine stumbles, pukes, and spits at part throttle.