Apparatus and methods for varying valve lift in an internal combustion
engine are disclosed. The apparatus include a rocker arm having an
elongate aperture and a shaft configured to pass through the aperture.
The height of the shaft with respect to the aperture is variable to
effect different rocker arm ratios when in combination with a fixed
fulcrum point. When the shaft is located in a lower position with respect
to the aperture in the rocker arm, the rocker arm pivots around the
rocker arm shaft producing full valve lift. Alternatively, when the
rocker arm shaft is positioned at a height above the lower position, an
upper surface of the rocker arm becomes engageable to varying degrees
with the fixed fulcrum point, allowing the rocker arm to pivot around the
fixed fulcrum point, thereby reducing the rocker arm ratio, and
corresponding valve lift dependent on the rocker arm shaft position.
Corresponding methods are also disclosed.