I have an older version of SolidWorks installed, but I've never used COSMOS before, and I can barely use it at all. Really only use it to pull dimensions from other people's models because the current drawing viewer from them doesn't dimension properly - not a problem unique to me either, lots of people have not been able to get the viewer to work properly.
Newmaticarsenal, nice work. Can you get some pics of the cupseal from an angle that shows where it meets the valve nut? The reason I'm worried about thread stripping in a thermoplastic in this type of valve - why I went to aluminum aside from being better at it - is that the powertube is being pulled away from the cupseal by the location of the spring. In a traditional Nelson valve train the two are in compression for a small dynamic portion of the cycle and not acting on each other a whole lot aside from the forces holding them together while at rest. I worry that it won't take too long for the PT to tear itself out of the cupseal as the seal makes a sudden stop and the PT wants to continue.
The powertube I posted I've had second thoughts on - the first portion of that meets the cupseal is good, but the ports should taper in the opposite direction. I think a plunge cut with a regular end mill at an angle, and perhaps a slight side cut would be superior. Something like this:
Plenty of port area and smooth flow. The removing part of the back end is intentional, it allows for higher flow potential earlier in the valve opening cycle. I think this is probably very much along the lines of what Alpha was saying he wanted to make.
The design of the valve that I've posted has an advantage to something Schmitti has touched on - it allows the PT ports to be fully exposed during the valve opening, that is why I have pictures of it up showing the ports fully exposed. The tapered inlet offsets the ports from the sealing point slightly allowing that to happen.