A low-leakage air valve assembly 10 for an air intake manifold 16 includes a butterfly valve 12 constructed for mounting on a rotatable shaft 14. The butterfly valve 12 includes a first 32 and a second wing 34 with first elastic sealing means 36 mounted about the periphery of the first wing 32, and second elastic sealing means 40 mounted about the periphery of the second wing 34. The first elastic sealing means 32 includes a projecting lip 38 for sealingly contacting the wall of the valve manifold 16. The second elastic sealing means 40 includes a beam portion 42 for sealing contact with shoulder 28 of manifold 16. Third elastic sealing means 44 is axially positioned at each side of the passage 30 in the butterfly valve 12 and radially provided around a portion thereof. The first area 54 defined by the first sealing surface which is the first wing 32 and first elastic sealing means 36 is larger than the second area 56 defined by the second wing 34 and second elastic sealing means 40. This provides a net torque which increases the sealing force of the valve.