Setting the float height on a Weber carburettor is important to the proper operation of the engine. Any time a new or rebuilt carburettor is used, the float height must be checked. A float level that is too high will cause the engine to run rich and may flood the carburettor with too much gas. A float that is too low will make the engine run lean and cause poor performance. Adjusting the float height is an easy task that does not require special tools or expertise.
Remove the fuel line, choke thermostat wire and carburettor flange mounting bolts. Remove the throttle linkage and lift the carburettor off the vehicle. Place a clean shop rag over the exposed intake manifold to prevent dirt and debris from entering the engine.
Remove the six retaining screws on the top of the carburettor. Remove the clip holding on the choke linkage. Be careful not to damage the clip. Remove the top of the carburettor. The carburettor may have gasoline inside the float bowl; drain any residual gas into a fuel proof container and dispose of properly.
Hold the carburettor at approximately a 45-degree angle and allow the float to hang freely. Measure the bottom of the float to ensure both sides are parallel to the gasket surface of the carburettor body. Bend the float to correct any warpage between the two sides of the float.
Hold the carburettor upside down so that the float is resting on the float valve. Measure from the bottom surface of the float to the machined gasket surface of the carburettor body. Bend the float tab until the reading is 1.5 inches or 38.5mm.
Install the top of the carburettor and tighten the six hold down screws. Attach the choke rod with the retaining clip. Remove the shop rag on the intake manifold and install the carburettor on the vehicle. Connect the fuel line, throttle linkage, choke wire and hold down bolts. Start the vehicle and check for leaks.
Gasoline is highly flammable. Avoid open flames or ignition sources when working around raw gas.