Camshafts and Compression

92b said
I'm not saying who is right or wrong. Mike seems to consider the load comes only from the spring. So higher lift equals more load.
I don't know how much the inertial forces are compared to the load from the spring but they must count for something.
These forces would come at the moment of highest acceleration (at or near valve opening) and are influenced by the mass of the objects being accelerated (weight of the valve assembly). Conversely, as the valve reaches the point on the cam lobe where the acceleration starts to slow, the inertia of the already acccelerated mass starts to take load away from the rocker tip negating spring pressure felt at the tip. This counter force would be greatest at or near the end of opening and the begining of closing or the point that the spring pressure is at it's highest. Again I don't know the quantity of that force (dependent on the mass and acceleration rate) and how it compares to the force from spring pressure.
But what if for arguments sake it is more than the spring pressure at the seat. This could mean that the load on the rocker is higher at beginning lift and lower at max lift.

I tend to think similarly and have never sat down to calculate the loads at different points but I think it’s really unnecessary (unless you’re building valvetrain components). What Mike is doing (and saying) is place the shaft at a location that eliminates sweep on the valve side, puts it on the pushrod side, run the longest pushrod you can to make the sweep minimal and then the loads (and ratio change, effective length) at the valve, as well as acceleration/deceleration of the valve at different lift points will all be as good as they can be and work in your favor.