The Edelbrock 18124 Thunder Series AVS 800 CFM manual choke EnduraShine carburetor has been designed and calibrated to deliver optimum street performance. Several characteristics make the 18124 Thunder Series AVS 800 CFM manual choke EnduraShine carburetor an outstanding street performer. The first one is that metering rods are utilized to transition between circuits. The carburetor is unaffected by engine backfires, which means that there are no power valves to blow out, and the rods can be changed in seconds without carburetor removal or fuel draining. Secondly, the carburetor has the unique ability to "hold a tune", so once it is tuned, the carburetor stay’s tuned. What this means to you is that compared to other carburetors, the performance remains consistent and the calibration stays unchanged. The third characteristic is the primary and secondary booster clusters that are utilized offer the most accurate and up-to-date calibration available for today's fuels and octane levels. Fourth the unique Thunder Series' Qwik-Tune Secondary Air Valve allows for limitless calibration of the secondary circuit with simple hand tools while on your vehicle. It's quick. It's simple. It's effective. It can be easily adjusted - in seconds - to suit your application... no extra parts required to achieve optimum performance. Simply put the Edelbrock 18124 Thunder Series AVS 800 CFM manual choke EnduraShine carburetor is undeniably the most innovative and dependable street performance carburetor available today. • Manual choke AVS® Carbs cannot be converted to electric choke • Thunder Series AVS Carbs will work with Ford automatic overdrive trans (AOD) when used with Lokar bracket SRK-4000 • Edelbrock carburetors are not calibrated for or compatible with alcohol, race or E85 pump fuel. The use of alcohol or E85 in your Edelbrock carburetor will damage your carburetor and void your warranty.