Mechanical valve design

[Motorhead]

No issue at all .. been using PEEK poppets on 6061 grade seats for years w/o issue .. 7075 is a lot tougher and primarily used for reduced wear at the stem area.

[JPSAXNC]

Thank You.

[nxp]

Trying to breath a little life back into this thread....

Based on what I've shared above, what adjustments to my design should I make?

The valve opens easy, check
. 
No stiction thanks to a good oring and good lube, check

100 yard accuracy is good, check.

Closing cycle manipulation, via chamber height/volume, it works, but I feel like something is missing. 

I can make the valve blow open much like a more controllable Cothran, by increasing chamber volume   I can make the valve close more like a standard unbalanced valve by reducing chamber volume.

What is lacking? With a Cobra valve in similar applications , when jetted "right", I can make the valve snap shut much sharper, much faster than a traditional poppet with heavy return spring. 

Those that have been there, done that......  understanding that making this valve was a major stretch of my fab skills, there is only so much that can be done with a drill press, files, sandpaper, and a dremel....  making a new valve will be a very heavy lift. 

How could I modify my existing valve, specs defined in posts above, with a goal of achieving a sharper, more snappy closing cycle?

Making a new valve is not out of the question, but I believe there is more to learn with this one prior to making a new one... 

Thanks in advance.

the cylindrical area around poppet is cruzial for pressure based fast closing. Should rise above poppet max height in a cylinder shape. As narrow as you can go here. Behind that is your plenum with air.  Poppet works in my opinion best when slightly concave (outer ring of head touches valve seat) and flush valve seat (90deg) , if you reduce poppet head height, you can reduce the cylinder height around it(think of it as piston in a cylinder) . Getting hammer speed up to max with high lift of poppet where closing time also is minimal due to high pressure (from spring and air) improves the fps dramaticly. Got above 1800fps on this way of tuning with .177 nsa 21gr slugs. @350 bar. Stable and safe with 300 bar , 1550/1600 fps. Know this thread is some days, hope my input can help other.
And toss that poppet pin o-ring- it expands under pressure, what you feel now is not the real picture when valve operates keep clearance low and you will reduce dwell time some on that to, oring is not optimal, if you must have, use tiny orings like those found inside cigarette lighters, and the oring seat must be sharp 90deg cut .