The clamp serves to position the mouth of an air duct against the surface of the exhaust manifold of an automotive engine so that hot air may be drawn into the duct. The clamp is a spring steel strap of U shape with shoulders at midlength of the limbs. Endwise of the shoulders the arms converge in a vee to accommodate various shapes of manifold pipes. The U neck of the clamp fits within the throat of the air duct, holding it by expansion, while the arms hold the exhaust manifold by contraction. The complete kit includes the clamp, an air duct, and a cover to enhance the collection of hot air. The kit serves to restore the hot air collection function in older vehicles which have lost original parts.