Why do 4-stroke engines need something to actuate the intake valve?
Consider a hit-and-miss engine. There's no external mechanism (like a cam) to actuate the intake valve. It's held closed by a light spring, and when the cylinder begins its intake stroke, the low pressure pulls the intake valve open.
Why then does a standard 4-stroke N/A engine need something to actuate the intake valve?
Submitted June 19, 2017 at 09:15PM by metrogdor22
via reddit http://ift.tt/2sMAhBY