With respect to an internal combustion engine equipped with a carburetor and a catalytic converter which requires to feed the engine with a stoichiometric air/fuel mixture, the control system is for regulating the air/fuel ratio produced in the carburetor and comprises an auxiliary air admitting passage...http://www.google.co.uk/patents/US4056932?utm_source=gb-gplus-sharePatent US4056932 - Control system for promoting catalytic removal of noxious components from exhaust gas of internal combustion engine
