I suffered from a valve train instability/harmonic issue a few years back that almost cost my a motor. Dwayne Porter traced the problem back to improper valve spring installed height and issues with valves spring tension versus the capacity of the hydraulic lifters available for big block Mopars to handle spring loads heavy enough to control the hydraulic lifters with out them collapsing from the pressures. My initial setup lost control of the valvetrain at around 5800rpm. A power dip was evident on my dyno sheet. Dwayne spotted it right off.

I switched to solid rollers to bypass the problem. I also used Mike at B3 Racing to get a geometry correction kit and ordered custom rocker arms from T&D to adjust my valve train geometry to a more optimum relationship and up-sized and upgraded my pushrods to a set of 7/16" Manton Stage 5 parts. Their customer service, tech advice and turn around time were great.

In the end, these changes gave me one of the smoothest reving and running RB motors I have ever experienced in 40 some odd years. My lash has only needed a minor(.001-.0015") adjustment in 3000+ miles. I usually shift below 7k rpm at the max, and there is an entire magnitude of harmonics or higher frequency vibrations that is noticably absent from this engine now. I believe it is due to the optimized valvetrain geometry, the stiffer pushrods etc. Almost all my previous 440's had the same noise/vibrations while reving.