valvetrain

The valvetrain includes the camshaft, lifters, followers, rocker arms, pushrods, retainers, springs and valves. It determines, along with the heads, how much air can pass into an engine. Most valvetrain system are very mild from the factory. This is why alot of horsepower can normally be extracted from a mild factory setup. The cam is usually the best place to extract power and can be purchased for a reasonable amount.