A Side-valve ingine is an internal combustion ingine wi valves placed in the ingine block beside the piston, insteid o in the cylinder heid, as in an owerheid valve ingine. As the cylinder cross-section haes the shape o an inverted L, ither names sic as L-block or L-heid are an aa common.
The side-valve ingine's poppet valves are uisually sited on ane side o the cylinder(s). A recess in the cylinder heid creates a corridor connecting the valves an the combustion chamber. The valve gear comprises a camshaft which operates the valves via semple tappets, maist commonly wioot ony faur valvetrain components (sic as pushrods, rocker arms, owerheid valves or owerheid camshafts).
The side-valve arrangement wis ance the maist common across aw motor industries (automotive, agricultural, marine, aviation, an others), but it haes syne fallen frae favour in maist multicylinder applications, sic as automotive an aviation, haein been displaced bi owerheid valve designs. Side-valve designs are still commonly biggit new for mony smaw ingine applications o ane an twa cylinders, sic as lawnmowers, rotary tillers, an twa-wheel tractors.