There's 2 intake valves, their area is combined, so is their lift. There are some flow losses, particularly at lower RPM(for the 4 valve engine), but all things considered, a 2 valve engine needs roughly twice the valve lift as a 4 valve engine to get roughly the same airflow.
When hotrodders talk about a .600 lift cam, they're talking about a cam that operates the pushrod 6 tenths of an inch. The rocker ratio plus the pushrod displacement gives you the effective valve lift.
On a overhead valve engine, there is no pushrod, only rockers/follower, or direct cam to valve action.
mikenigger 0 points 2.3 years ago
who cares, ya'll be drivin' electric shavers in 10 years