Abstract: An engine air intake shut-off valve utilizing a loose-fitting gate member is disclosed. The shut-off valve is of the sliding gate type in which a gate member is reciprocable between an open and a closed position. The gate member is dimensioned smaller than the interior of the valve housing to provide a clearance for smooth operation after dirt has accumulated in the housing. The gate member is loosely connected to a reciprocating cylinder which permits the gate member to move along the direction of air flow to seat against either of two opposed seating surfaces in the valve housing.