The Edelbrock AVS2 Off-Road Carburetor #1915 with Manual Choke is a special 650 CFM version of the proven #1905 street carb with Annular Flow Booster technology for near-EFI-like drivability that you can feel as soon as you step on the gas. Like AVS2 street carbs, the AVS2 Off-Road features an annular ring with eight orifices that replaces the standard single brass tube (down-leg) fuel feed. The AVS2 Off-Road booster ring distributes fuel into the airflow stream with an even spray that eliminates flat spots and greatly improves throttle response in the low- to mid-RPM range without sacrificing top-end power.For superior fuel control over rough terrain, the AVS2 Off-Road features a new spring-loaded needle and seat along with a spring-loaded anti-syphon ball in the accelerator pump circuit to prevent fuel drip common with standard carbs in off-road situations.The AVS2 Off-Road is unaffected by engine backfires since there are no power valves to blow out. For fast and simple part-throttle tuning, metering rods and springs can be changed in seconds without carburetor removal or fuel draining. AVS2 Off-Road carbs have the unique ability to "hold a tune” when compared to other carburetors. Your tuning and adjustments stay unchanged, so performance remains consistent. Updated primary and secondary booster clusters in the AVS2 Off-Road offer the most accurate and up-to-date calibration available for today's fuels and octane levels. Additionally, the unique Qwik-Tune Secondary Air Valve allows for limitless calibration of the secondary circuit. Adjustments can be with simple hand tools in seconds to suit your application.AVS2 Off-Road Carburetors feature a two-piece design for easy tuning that allows you to make float level adjustments or replace internal components without draining the carburetor or removing it from the engine. The AVS2 Off-Road 650 CFM is available with a manual (#1915) or electric (#1916) choke and is manufactured by Edelbrock in the USA.