Abstract: An internal combustion engine designed to use gas as fuel. Exhaust valve (2) operation is effected via: (i) a push rod of two parts, the respective ends of which are pivoted to an intermediate connector sliding in a bore in the cylinder head and (ii) two rocker arms (11 and 16). Fulcrum point (18) of rocker (16) may be adjusted to reduce exhaust valve lift during part throttle operation or alternatively exhaust braking during overrun conditions may be achieved by cracking open valve (2) on the compression stroke: this is effected by inward movement of wedge (21) or by a cam raising the end of rocker (16). Modifications of exhaust manifold, rocker shaft mounting, etc are also described.

Abstract: A modified carburetion and manifold arrangement to enable internal combustion engines to efficiently use fuels such as alcohols having high latent heat of vaporization. A variable venturi carburetion means (30) is combined with two manifolds-one (20) being larger for use during medium to high power operation and a second smaller manifold (24) for starting and low power operation.

Abstract: An ignition system for internal combustion engines which minimizes or eliminates problems associated with conventional spark ignition arrangements, the ignition system comprises a laser energy generator (9) which is arranged to supply laser energy continuously at an energy level less than that needed to initiate combustion with the energy level being spiked in timed sequence and delivered to the combustion chambers (35) of the engine, the system further including optic means (39) for focussing the pulsed laser energy at predetermined points within the combustion chambers whereby the focussed laser energy is sufficient to ignite any combustible charge within the combustion chambers, the pulsed laser energy being deliverd through a purging chamber (12) to the respective combustion chambers with a purging gas being continuously supplied to the purging chamber (12) to prevent combustion gases flowing towards the laser optic means (39).