What is a Camshaft?

You could say that a camshaft is the mechanical brain of your engine. The camshaft is a long billet steel or metal shaft that has lobes ground into it. When the engine is running the camshaft spins around and the lobes open and close the valves. The camshaft lobes open and close the valves at the precise moment to let fuel and air in and then let spent gasses out, after combustion happens. With a greater lift and duration on the camshaft lobes the engine can ingest & process more air and fuel to make its efficiency go up on every power stroke the piston makes. (Definitions supported/ found on answers.com)