Procision-Auto wrote:What about the angle of the pushrod as the rocker pivots?
The pushrod moving away from the "centerline", or resting position.
We could probably do some trig and figure out how much the PR angle
takes away from the valve lift when the cam lobe is at peak lift.
As the pivot point gets closer to "c", the small changes on the pushrod
side are multiplied at the valve side and vice-versa.
Procision-Auto wrote:I'm going to disagree with you there. Since the pushrod length is fixed,
and the cup distance (to fulcrum) is fixed,
Speedbump wrote:I've never thought about it and I'm not sure what their quick lift idea is but what is explained in the diagram makes sense to me and that's a little scary. If the pushrod cup is below the centerline of the pivot, it has to move laterally away from the center until it reaches the c/l which makes the ratio lower and the leverage higher. After the cup passes c/l, the ratio has to increase since the cup travelin the arc is moving closer to the pivot point. The tip, if it starts above the c/l moves away from the centerline of the pivot and that also increases ratio, but as soon as it passes through the c/l of the arc the ratio starts to decrease. This should happen at 1/2 lift if the geometry is correct, right? So, does Crane move the cup up toward the c/l of the arc and call it quick lift? I find this stuff very interesting and geometry is the only math class I did worth a darn in so I hope I'm seeing this right.
Alex W wrote: The more the rocker sweeps the longer the length of the red line "d" grows. Making the ratio increase as the valve is lifted.
bigjoe1 wrote:I think they got it backwards from what I would like to see. I never use them on anything.
JOE SHERMAN RACING ENGINES
Alex W wrote:This is correct. Would you not call that distance "c"? Since "c" is the radius of the PR cup to the fulcrum(shaft). Now since "c" is a radius of a circle its distance never changes there for lift at the PR side of the rocker will not change either.