Quote: I played around with this stuff years ago looking to see what happened when I set up the valve train to achieve different end goals. It's not just a "peak lift thing"; you can also measure differences in net duration at various points across the lift curve, as well as variations in the scrub patterns and where in the lift curve the majority of the scrubbing takes place.
Now, if you asked me what my findings were... I can't tell you where those notes ended up, nor would I claim my "testing" was precise enough to make any specific claims one way or the other.
I will say that the final configuration I worked out for those Stage VIs resulted in a nicely centered sweep across the valve tip that was somewhere in the .050-.060" width range over .600" lift. It followed Jim Miller's Mid-Lift concept, rather than Jesel's, and the guides showed basically no wear after about 5K miles when I sent the heads back to Dwayne Porter to be touched up.
To get maximum lift from the cam lobe, the rocker would have to be at 90 degrees at full lift where there is no wasted motion from the sweep. Unfortunately, that is where the valve is at its highest acceleration and valve float occurs. The rate of lift is also very slow at lower lifts which keeps the valve close to the seat longer where the air flow is worse. Not good for performance.
Just to clarify, a sweep pattern across the valve tip is way different than actual measured sweep. The sweep pattern shows the footprint of the roller plus the sweep, where the measured sweep will be sweep only. This example would have only been about 0.25"-.030" measured.
Mike Beachel
I didn't write the rules of math nor create the laws of physics, I am just bound by them.
