ove, or over the cylinder head instead of inside the block. This arrangement has an advantage of eliminating the added weight of the rocker arms and push rods. The rocker arm setup is operated by the camshaft lobe rubbing directly on the rocker. Stem to rocker clearance is maintained with a hydraulic valve lash adjuster for "zero" clearance. A double overhead camshaft is the same as an overhead camshaft, except its two instead of one. The double overhead camshaft is a bit heavier than a single one, but puts out twice the amount of ability. In an overhead valve engine, the valves are mounted in the cylinder head, above the combustion chamber. The timing refers to the delivery of the ignition spark, or the opening and closing of the engine valves. More accurate timing results in better performance of the vehicle when needed. (Auto 101)The combustion chamber is where the air-fuel mixture is burned. The location of the combustion chamber is between the top of the piston and the cylinder head. TDC is the pistons position when it has reached the top of the cylinder. The two most commonly used types of combustion chambers are the hemispherical and the wedge shape. The hemispherical type is compact and allows high compression with a minimum of detonation. In the hemispherical type of the combustion chamber, the valves are placed on two planes, enabling the use of larger valves. The wedge type of the is part of the cylinder head. Its very more efficient than the hemispherical chamber. (Auto 101)There are four different strokes that the pistons make. The first of the strokes is the intake stroke. The piston moves down the cylinder and creates a partial vacuum in the cylinder. A mixture of air and fuel is forced through the inlet valve into the cylinder by the atmospheric pressure. The second stroke is the compression stroke. The piston moves up the cylinder with both valves closed. The third stroke is the power stroke. The ...
