Webcon supplied 'pump spill' valve, sometimes called a 'back bleed valve, part number 79701.

It is fitted in the float chamber of many Weber carburettors including the DCOE/IDA/IDF/ICH ranges.

It is a calibrated part from 0 to 100.

The larger the number the more fuel is bled back to the float chamber when the pump jet is operated.

The size used depends on the pump rod length & pump jet size.

The 'zero' valve is often used to eliminate 'flatspots' under acceleration & used widely in competition applications.

Sizes vary from 0,35,40,50,60,70,80,90 &100.