Its the calculation part, the math that's out of reach, fore me anyway.
So if you have that part figured out please bee so kind and enlighten me.
Not too many car guys are NASA level engineers, trained in the mathematics of inertia/load etc. Not saying Brent isn't capable of that, he's a pretty smart guy, but that's pretty complicated stuff that has a hundred parameters that affect outcome. Rather, most of this stuff comes from observation and experience based on repetition, or the experience of others that share their data about valve float given certain combinations or ramp design, valve and retainer weight, rocker weight (which, like Brent pointed out, isn't about total weight, but rather the weight that extends outside of the rotational axis) etc. When you have a collective knowledge that shares info, like has happened on the FE forums over many years, with many shared dyno experiences, you just form a basis of knowing what might/will work and what might/will not. I'm pretty sure the engine guys on the forum will readily admit that their knowledge base grows with every engine they build, not some set mathematics formula. That's one of the great things about the 'dyno' page on this forum. It's a great place to compare combinations and see what really works well together.
That's probably about as good as I could put it.
I'm a degreed mechanical engineer, but the amount of statics/dynamics involved in calculating something like that would be extremely in depth and would probably be only done accurately with the help of FEA software.
In some cases, it's easier to just try things on the dyno, or on the Spintron.
I built a 556 cubic inch BBF pulling truck engine for a customer that essentially had an operating rpm range of up to 9000 rpm. I had contacted my Comp rep as well as my Trend rep to see about taking my camshaft/heads/etc. to them and spending a day on the Spintron. Unfortunately, neither one of them had a BBF block there with 60mm camshaft journals. Comp used to have one but Kaase took it home (thanks Jon...).
The Spintron takes a special block that has basically been cut up. There is no rotating assembly involved; it's essentially just an empty block with a camshaft in it, topped with heads and valvetrain, driven by an electric motor. The valvetrain is spun up to whatever rpm levels are required and data is collected to see what changes need to be made. I'm sure Mr. Conley could fill us in and speak more at length about it.
Since the Spintron was not available to me, I got on a conference call with my Comp rep and one of the higher-up design guys and gave them every single bit of information that I had, down to the weight of the valve locks......weights of the lifters, valve springs, valve spring pressures at install height, rocker arm weights, rocker arm materials, pushrod lengths and diameters, valve sizes and weights, etc, etc. Once all the data was given, the phone call was ended. I received an email a few days later stating that the camshaft lobes that I had selected, in combination with the valvetrain parts that I was using, was capable of 10500 rpm.
Sometimes it takes experience and lots of data collection to find something that works and works well.
