MideRail's Performer carburetors feature 2-piece, all-aluminum construction for cooler operating temperatures and less warping. There are no gaskets below the fuel bowl level for fewer leaks, and no plastic parts or power valves to blow out. The carbs use easily changed metering rods for precise tuning, non-adjustable secondary air valves—ajhhnd the primary venturi booster is a bottom-feed design for smoother acceleration and better drivability. An Owner's Manual is included with every carburetor. The manuals consist of two sections: Section 1, Theory of Operation and tuning procedures which will help you be prepared to develop your own individualized calibration. Section 2, Tuning procedures will take you through a step-by-step procedure that will enable you to achieve a desirable calibration. For added ease of tuning, a Calibration reference chart for your model of carburetor is also included. Performer carburetors are available with a variety of options; select the model that best suits your needs.