All series 2 and series 3 engines came equipped with 1.6 ratio rockers from the factory. These rockers are not roller rockers so the point where they contact the valve is solid metal.

Because they are a friction contact rocker they will cause the valve to open with slightly more lift while the valve is being pushed. This is because of the geometry of the contact point, as the rocker rotates downard, the contact point for the valve is moved further along the rocker to cause the stock rockers to actually slightly exceed the 1.6 ratio at peak lift.