Beehive valvesprings on all roller 408 smallblock

Thanks Moper, that's the best explanation I've ever heard. I saw something like that at a diesel engine OEM once, but I understand it alot better now. There was a spring pulling the fan belts tight. Turns out, it's natural frequency happened to be the same as the engine at high idle. You could actually see a shockwave bouncing back and forth down the spring. When it got to the end, it would bullwhip the last coil, which would inevitably snap in a few hundred hours.