Compared with OHV pushrod systems with the same number of valves, the
reciprocating components of the OHC system are fewer
 and have a lower overall
 Though the system that drives the camshafts may be more complex, most
engine manufacturers accept that added complexity as a trade-off for better
engine performance and greater design flexibility. The fundamental reason for the OHC valvetrain is that it offers an increase in the engine's ability to exchange induction and exhaust gases. (This exchange is sometimes known as "engine breathing".
 ) Another performance advantage is gained as a result of the better optimised port configurations made possible with overhead camshaft designs. With no intrusive pushrods, the overhead camshaft cylinder head design can use straighter ports
 of more advantageous cross-section and length. The OHC design allows for higher engine speeds than comparable cam-in-block designs, as a result of having lower valvetrain mass. The higher engine speeds thus allowed increases power output for a given
Disadvantages of the OHC design include the complexity of the camshaft drive, the need to re-time the drive system each time the cylinder head is removed, and the accessibility of tappet adjustment if necessary. In earlier OHC systems, including inter-war Morrises and Wolseleys, oil leaks in the lubrication systems were also an issue.