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Although an overhead camshaft (OHC) engine also has overhead valves, the common usage of the term "overhead valve engine" is limited to engines where the camshaft is located in the engine block. In these traditional OHV engines, the motion of the camshaft is transferred using pushrods (hence the term "pushrod engine") and rocker arms to operate ...
Some OHC engines employ short rocker arms, also known as finger followers, [2] in which the cam lobe pushes downward on the back of the rocker arm to open the valve. In such a configuration one end of the follower is anchored (pivoting in place on a roller bearing), rather than having its fulcrum in the center like standard rocker arms.
SOHC design (for a 1973 Triumph Dolomite Sprint) . The oldest configuration of overhead camshaft engine is the single overhead camshaft (SOHC) design. [1] A SOHC engine has one camshaft per bank of cylinders, therefore a straight engine has a total of one camshaft and a V engine or flat engine has a total of two camshafts (one for each cylinder bank).
Pushrods are long, slender metal rods that are used in overhead valve engines to transfer motion from the camshaft (located in the engine block) to the valves (located in the cylinder head). The bottom end of a pushrod is mated to a lifter, upon which the camshaft makes contact. The camshaft lobe moves the lifter upwards, which moves the pushrod.
In 1994, all 2.2-liter engines were updated to sequential multi-port fuel injection and power increased to 120 hp (89 kW), with torque increasing to 140 lb⋅ft (190 N⋅m). The MPFI and SFI versions produced enough power to allow the 2.2 to replace the old Pontiac Iron Duke engine as the 4-cylinder offering in the S/T trucks and A-body cars.
Though it was designed as a pushrod engine, it was advanced for the time. [1] The pushrod version of the Lancia boxer was only ever used in the Flavia, and its derivatives including the Lancia 2000. In 1976, a new overhead cam engine based on a similar layout was designed and brought into production in 2 and 2.5-litre displacements for the Gamma.
The lobed camshaft rhythmically presses against the lifter, which transmits the motion to the engine valve in one of two ways: through a pushrod which actuates the valve via a rocker mechanism (in an overhead valve (OHV) engine); via direct contact with the valve stem or rocker arm (in an overhead camshaft (OHC) configuration).
At the beginning of 1984, Ford Pinto engine displacement range switched from 1.3/1.6/2.0 to 1.6/1.8/2.0. The newly introduced 1.8 L engine used the 2.0 L crankshaft, so to uniform engine parts for the whole range after dropping the 1.3 L — the 1.6 L was redesigned to also take the 2.0 L crankshaft which had a 76.95 mm (3.030 in) stroke.