ivymike - you're correct about my "force on the cam lobe" statement, it was off the cuff and incorrect. More correctly, I should have said: 'the spring Force must be >= Force necessary to keep the valvetrain from seperating = effective valvetrain mass * cam profile acceleration'
(And I did mean 'effective' valvetrain mass, considering the inertia of the rocker arm, the multiplicative effect of the rocker lever on the other masses, as well as the effective mass of the spring)
I'll see if I can get some time to work on the pushrod problem. It looks like fun!
Another question - to determine the energy in the harmonics generated by the cam profile, do you simply take the Fourier transform of the physical shape? What does a 'typical' transform look like? Both even and odd harmonics? Does the energy die off quickly or have a significantly long tail? It would make sense why lobes have a pseudo-gaussian shape though (maximum localization of the time-frequency spectra).
