Valve float, where the valve fails to close fully, is more likely to occur at high RPMs with weaker springs. This can lead to poor engine performance and even damage.

The two-cylinder layout is exceptionally common in the world of motorcycles. This Ducati has the most powerful two-cylinder ...

As the engine heats up, the spring inside the thermostat expands and pulls the valve open. Electric chokes use the vehicle's 12-volt power to control the thermostat.

One downfall, however, is their ability to rev. Pushrod engines tend to have rather low redlines. You won't find a GM small-block V-8 revving to 9,000 rpm, but there's a reason for it all.