As the name implies, OverHead Valve engines (OHV) have the valves located above the combustion chamber, in the roof of the cylinder head.
The OverHead Valve layout permits smoother fuel mixture intake, plus quicker and more complete exhaust. This increased combustion efficiency, in turn, enables a higher compression ratio to be used. In this way it is possible to obtain a greater power output and to avoid the build-up of carbon.
The OHV-design gives also an excellent thermal balance, which contributes to reduced cylinder distortion, a decrease in oil consumption and an increase in engine service life.