Abstract: A unitary structure for a vehicle engine which provides an air cleaning function, a fuel vapor storage function and a valve cover function. The structure may be molded or cast in a configuration particularly adapted to be secured to the outer portion of an engine cylinder head thus forming an enclosure means for valve components such as rocker arms and a camshaft if the engine is an overhead cam type engine. First and second wall means are spaced progressively outward from the cylinder head to form a space therebetween adapted to hold a quantity of activated charcoal. The charcoal is connected to the fuel tank and carburetor to trap and store fuel vapors therefrom. Another space is formed above the second wall means to house an air filter element. Air inlet and outlet means are located below and above the filter element to provide for a flow of air to the engine carburetor.