Air-cooled reciprocating internal combustion engine with removable individual heads for multiple cylinders

In an internal combustion engine having at least two side-by-side cylinders associated with a common metallic block, the improvement comprising

• (a) first and second heads separately connected to, and detachable from the respective cylinders,
• (b) and rocker arm assemblies including shafts carried by said heads to pivotally support valve controlling rocker arms,
• (c) each head including sections which are removably interconnected, one section removably connected to the cylinder and defining valve seats, and the other section carrying said rocker arm shaft,
• (d) each of said cylinders having an axis, said two axes being parallel, each pair of said sections interconnected along a first plane which extends at and angle .alpha. relative to said cylinder axes, .alpha. being about 58.degree., and including a cap removably attached to said other section, and a looping seal between said cap and said other section, said seal everywhere located above the level of an oil drain sump zone defined by said other section, said cap joined to said other section along a second plane which extends at an angle .beta. relative to said said first plane, .beta. being between 10.degree. and 55.degree.,
• (e) each said one section having a first side which is relatively large and a second and opposite side which is relatively short as determined by said angle .alpha., said one section defining, proximate said first side, an intake air/fuel mixture flow duct which extends, with smooth curvature, generally lengthwise of and through said one side and toward an intake valve seat spaced from said cylinder,
• (f) there being valve stems actuated by said rocker arm assemblies, the valve stems solely carried by said head one section via valve guides which are generally in lateral registration with the longitudinal intersections of the flow duct with said first side.