1. pistons
   lobes
2. cylinders

The key parts of any camshaft are the lobes. As the camshaft spins, the lobes open and close the intake and exhaust valves in time with the motion of the piston.

1. single overhead cam
   pushrod
2. platinum overhead cam

The most common types of camshafts are the single overhead cam, the double overhead cam and the pushrod.

1. crankshaft
   timing belt
2. timing chain

Cams are driven by the crankshaft via a belt or chain (called the timing belt or timing chain) in single and double overhead cam engines.

1. 2
   4
2. 3

A double overhead cam engine has two cams per head, so inline engines have two cams and V engines have four.

1. Pushrod valves are located in the head.
   The valves are spring loaded.
2. The camshaft is located inside the engine block.

Like single overhead cam and double overhead cam engines, the valves in a pushrod engine are located in the head, above the cylinder. The key difference is that the camshaft on a pushrod engine is located inside the engine block, rather than in the head.

1. Honda
   Ford
2. Toyota

VTEC (Variable Valve Timing and Lift Electronic Control) is an electronic and mechanical system in some Honda engines that allows the engine to have multiple camshafts.

1. keeps valves open longer
   opens and closes valves later
2. opens the valves sooner

Some cars use a device that can advance valve timing. This doesn't keep the valves open longer; but it does open them sooner. This is done by rotating the camshaft ahead a few degrees.

1. It regulates the amount of fuel and air that enters the engine.
   It monitors the pistons.
2. It controls the action of the engine valves.

The motion of the camshaft controls the action of the engine valves, which then regulates the amount of the air/fuel mixture that powers the engine.

1. rocker arms
   springs
2. valves

The cam actuates rocker arms that press down and open the valves. Springs return the valves to their closed position.

1. corrosion
   valve clogging
2. imperfect timing

The biggest design challenge with camshaft systems is varying the timing of each valve to maximize efficiency.