Rocker cover

Engines with more than one head (such as a V8) will have multiple rocker covers.

On engines without rocker arms, such as some overhead cam and most dual overhead cam types,[1] they are known as rocker boxes in the United Kingdom.

Very large multi-cylinder engines, such as those used in a ship or in aviation, may have one rocker cover for each cylinder, to make removal and installation more manageable.

Rocker covers did not exist in early engines, which had exposed intake and exhaust valves (for ease of lubrication).

With the advance of central lubrication rocker covers were added to keep the oil in and dirt out.