Automotive Valve Assembly

In a basic engine construction, there exist at least two valves, an inlet valve and an exhaust valve. The inlet valve of your engine opens just before the suction stroke, and the exhaust valve opens just before the exhaust stroke. The inlet valve allows your engine to suck fresh air-fuel mixture for combustion, and the exhaust valve releases burnt gases after combustion. You may find any one of the following valve trains on your engine-

 a. Overhead-Valve Engines: If your engine is an overhead-valve engine, then you will find valves in the cylinder head of your engine, and the cam shaft in the cylinder block. In case of an inline engine, you will find valves in a single row, and in V-type engine valves may be in double rows in each bank, or in single row in each bank. If your vehicle engine is of V type, then you must remember that one row contains intake valves and the other row contains exhaust valves.

Automotive Valve Assembly

b. L-head Engines: In case of an L-head engine, you will find the camshaft and valves in the cylinder block of your engine. In early days, this type of arrangement was highly popular for automotive engines. Now a day, this type of valve arrangement is used in small engines like lawn mowers. L-Head engines have some drawbacks. This type of engines can to accomplish high compression ratio. Another mentionable drawback is that it cannot achieve complete combustion of air-fuel mixture, and the flue gas contains too much partially burned and unburned gases.

c. Overhead-Camshaft Engines: This type of engines has become practical in newer engine designs. If you have such an engine, then you will find camshaft on the cylinder head of your engine. This type of engines is highly beneficial as they resist changes in direction and speed. If you closely look to the engine action, then you will find that push rod and rocker arm bend slightly before opening the valve. In case of DOHC (Double Overhead-Camshaft) engines, you have to remember that one camshaft operates the suction valve, and the other one operates the exhaust valve. In case of a V-type engine, you may find one or two camshaft in the cylinder head.

 d. Multivalve Engines: What is a multivalve engine and how it is beneficial? Basically, multivalve engines have 2-6 valves per cylinder. Two and four valves are most common in the recent time. In modern engine designs, you will find four valves per cylinder. This increased number of valves boosts power output and improves engine breaching. This arrangement allows more charge to enter into the cylinder, and aids to remove the exhaust gas easily than two or three valve engines.