What is cams on a car?

CAMS, or more accurately, the camshaft(s), in a car engine are rotating shafts that control the opening and closing of the engine's valves. These valves allow the intake of air and fuel mixture (or just air in some engines) and the exhaust of burnt gases. The timing of this opening and closing is crucial for efficient combustion and power output.

There are different types of camshaft systems:

* Overhead Cam (OHC): The camshaft is located in the cylinder head, above the valves. This is a common design in modern engines. It can be single overhead cam (SOHC) with one camshaft controlling both intake and exhaust valves on each cylinder, or double overhead cam (DOHC) with separate camshafts for intake and exhaust valves.

* Pushrod/Rocker Arm System: The camshaft is located in the engine block, and uses pushrods and rocker arms to actuate the valves. This is a more traditional design.

In short, the camshafts are critical components that precisely control the timing of the engine's breathing, directly impacting its performance and fuel efficiency.