22XX valve mod

[Trophyhunter49]

  Has anyone done this to the 22XX valve when changing over to bulk fill with HPA ? 

[Trophyhunter49]

  More pics.  The last pic. is ready to go back in with it being pinned on the sides!

[quickster47 †]

Yes.

Carl

[Trophyhunter49]

Yes.

Carl

could you tell any differnce??

[quickster47 †]

could you tell any differnce??

I really could tell no difference but I was hoping for a big difference because I thought the larger opening would be better for air to flow.  With CO2 it might make a difference because CO2 particles are larger than oxygen particles.

And I actually spent an hour polishing up all the internal parts to a mirror finish to improve air flow.   

Carl

[Trophyhunter49]

   All I could tell the it gave me a few more shots on a fill !!

[1377x]

Nice work

[onebaddj]

I worked a 2250 valve to the tilt and never got anything out of it. I cut off the peircing pin, bored out the valve, bored out the inlet, angled and bored out the transtlfer port, polished the valve stem.everything you could do to it and never got it to run better than a stock valve on hpa. Still have it but after all that nothing improved. Still dont make sense.

[quickster47 †]

When you switch over from CO2 Powerlets to HPA the valve changes function from what it was originally intended.  That's why all the valve work done to a stock Crosman 2240 style valve doesn't make any significant performance difference when running HPA.

Carl

[Trophyhunter49]

  I was sure thing that it would help with the power but all I got was a few extra shots out of it !! Goin to try some other stuff to it and see where it goes from there!! 

[quickster47 †]

Here is the way the valve works when using a Powerlet which is very different from when using HPA.

What happens inside the valve is that it acts as an intermediate holding chamber, for a specific volume of the compressed gas coming from the Powerlet.  When the hammer slides foreword and strikes the exhaust valve stem it opens the outlet of the valve, dumping an amount of CO2 from the holding chamber up into the transfer port and further on up into the barrel behind the pellet, where it is free to expand in only one direction, pushing the pellet out of its' way ahead of it and down the barrel.  Also the instant there is a pressure drop between that of the gas in the Powerlet and the pressure of the gas in the valve, gas rushes out of the Powerlet into the valve to equalize the difference.  Luckily for us, the entire volume of the valve is not released when this happens because there is an opposing spring that closes the valve.

The longer the valve stays open the more gas is released, the more expansion occurs, the faster the pellet comes out of the barrel, but at the expense of more gas used.

And all of this works because the contents of the Powerlet are 12G of compressed liquefied carbon dioxide and not gaseous carbon dioxide.

Softening the hammer spring causes the hammer to not hit the Exhaust Valve as hard, thus opening the valve for a shorter period of time, and less gas is released, and results in lower muzzle velocities, but more usable shots out of a Powerlet.

Now what I just described all gets thrown out the window when you remove the Powerlet and add an HPA tank.

Carl

[Trophyhunter49]

  Then its a hole new ball of wax!

[quickster47 †]

Forgot to say that in using HPA there are two things that probably do make a bit of a difference.  Cleaning and opening up the air passage in the valve body and using something like the Disco exhaust valve which has no significant protrusion on the face.  Where as when you use an OEM 2240 style exhaust valve and cut off the piercing pin you leave that large nipple on the front of the exhaust valve.

Carl

Picture shows different stages of exhaust valve trimming.

[Trophyhunter49]

 

[onebaddj]

No kidding. I did not realize that the hpa would work completely different than co2. I always thought the theory of operation would be the same. Get the air through the valve smoother faster and with more volume would increase velocity. This is interesting cause i just got the bulk fed half of the 2250 thrown together with a disco front end and boss valve rear end and disco pin. I just need a co2 tank to run it and i will be done as long as there are no leaks.

Thanks for the info!