Abstract: Apparatus for use in repairing internal combustion engines by admitting air under pressure into selected cylinders of the engine comprises a manifold including an inlet fitting for connection to a source of compressed air, at least two primary outlet fittings on the manifold, two corresponding primary spark plug hole fittings, and primary hoses connecting the primary outlet fittings to corresponding ones of the hole fittings to provide at least two primary air circuits. The manifold also has at least one secondary air circuit comprising an outlet fitting including a normally closed check valve, at least one secondary spark plug hole fitting and a secondary hose connecting it to a nipple fitting which can interlock with and open the associated check valve. With four secondary circuits the apparatus can be used with a large variety of engines, including in-line 4 and 6 cylinder; 2, 6, or 8 cylinder V-type, and 4 and 6 cylinder opposed type.