Valve Train Stability
M.Beyerstedt | June 24, 2011
Why doesn’t the valve do what it’s supposed to do?
By Gary Lewis, Dema Elgin and Rich Olivier
When building performance engines, we often ask a production engine to go well beyond where it was intended to go, both in output and in RPM. Since we did not design the engine, we are limited to selecting improved components and otherwise doing the best we can with what we have.
In regard to the valve train, we do have much more information available to us as a result of the camshaft analysis tools now widely available. This data tells what the valve should do as it travels through the cycle from opening, to wide open and on to closing. Add a rocker arm or follower ratio and superimpose that valve open curve over the cam lobe lift curve and there will be another clean, somewhat taller curve showing the motion of the valve through the same open cycle. In a perfect world, the valve motion would match the data generated curve but in reality, the actual valve motion will be different than predicted (see Fig.1). Continue Reading »

