The float pull clip, fastened to the float valve, hooks over the edge of the float arm at the center. Its purpose is to assist in lifting the float valve off its seat whenever fuel level in the float bowl is low.
CAUTION: Do NOT place pull clip through small holes in top of float arm. Severe flooding will result.
Fuel filter check valve is an "anti-rollover" safety device keeping the fuel from leaving the fuel tank through the carb at an accident.
The non-windowed inlet valve were introduced so that all fuel will be discharged over the top of the float valve seat. This provides a smoother flow of fuel through the float valve seat to control fuel turbulence in the float bowl.
And, if an original fuel pump is used, it has an anti-drainback valve built into it keeping the fuel in the float bowl before it evaporates.