22xx valve mods

[alex77147]

sounds like its time to make a custom metal threaded transfer port

yeah, I don't have the equipment though.  I'm thinking I might jbweld the polytube to the valve and leave the other side.

[1377x]

who modded your valve? if not self-modded, then maybe the modder can do one more mod for you

[alex77147]

who modded your valve? if not self-modded, then maybe the modder can do one more mod for you

I did most of it myself but Lloyd did work on the valve. 

[1377x]

maybe a pm/e-mail to Lloyd will get that metal tp you need.if you have another idea i would like to hear it.im getting a discovery valve modded to the max for a .32 pistol build i have planned.i should have asked Lloyd to do the work but went with a different modder.ill prbably get 2 shots per fill.the valve will be retained by 1/4-28 hs screws to get full use of the air being expelled i might just make it a rifle with a 28" barrel

[alex77147]

maybe a pm/e-mail to Lloyd will get that metal tp you need.if you have another idea i would like to hear it.im getting a discovery valve modded to the max for a .32 pistol build i have planned.i should have asked Lloyd to do the work but went with a different modder.ill prbably get 2 shots per fill.the valve will be retained by 1/4-28 hs screws to get full use of the air being expelled i might just make it a rifle with a 28" barrel

Man I can't wait to start my .357 project(will also most likely be a disco or 22xx platform), yeah Lloyd did a very good job with the valve, I will try a couple more things with the t port before I bug him again. 

[1377x]

cool! a .357 project huh?
i was going to do one but the guy modding my valve said why go .357 if you go .32 then you can use a variety of ammo from .308-.313
i also want to use a 28" barrel.read somewhere the longer barrel is best for airgun use???
the most important part is to enjoy it

[alex77147]

cool! a .357 project huh?
i was going to do one but the guy modding my valve said why go .357 if you go .32 then you can use a variety of ammo from .308-.313
i also want to use a 28" barrel.read somewhere the longer barrel is best for airgun use???
the most important part is to enjoy it

.32 is fine but I want a 9mm, and yeah a longer barrel helps velocity with big bore stuff.  And Yesterday evening I fixed the t port issue, I drilled out the connector out of a 1/4" plastic tube from a wire stripper set and cut it to proper length then wrapped a whole bunch of thread tape around it.  That tubing is very stiff and I took a few shots at my phone book and it held(didn't leak).  Now lest see if it will hold for some further testing.

[alex77147]

Ok so another update, gun is now at 55fpe when filled to 1750psi using a heavy hammer spring(871fps with 32.4 eun jin).  With the original disco spring i'm maxing out at 45fpe when filled to 1750psi.  First shot with the disco spring is 747fps with eun jin 32.4gr, second is 779fps, third is 795fps, and fourth is 779fps.  I didn't bother shooting past that.  What do you all think? almost condor power right?

[rsterne]

That's excellent power at 1750 psi.... How many shots are you getting per fill, and from what size tank?.... Are you running regulated or not?....

Bob

[1377x]

[lloyd-ss]

Ok so another update, gun is now at 55fpe when filled to 1750psi using a heavy hammer spring(871fps with 32.4 eun jin).  With the original disco spring i'm maxing out at 45fpe when filled to 1750psi.  First shot with the disco spring is 747fps with eun jin 32.4gr, second is 779fps, third is 795fps, and fourth is 779fps.  I didn't bother shooting past that.  What do you all think? almost condor power right?

Alex,
That sort of inverted bathtub velocity curve is to be expected.  Because the seat of the valve has been drilled out, it has more force from the air holding it shut.  [Force (in pounds) holding the valve shut = psi x area of the valve throat in sq ins]  Therefore, the stock disco spring has a harder time opening the valve when is has full pressure in it.  As the pressure drops with each shot, it is easier for the spring and hammer to open the valve so the velocity starts rising.  Then as the pressure continues to drop the velocity will start to fall off. 
Basically, drilling out the valve seat (throat) shifts the peak of the velocity curve to a lower pressure, in the same way that installing a weaker spring does. 
You have persevered and are doing excellent work. (YEA!) Keep good records and plot the data in excel like Bob does.  After you plot the data for different set-ups you will start being able to predict what results certain changes might produce and will gain an understanding of cause and effect with the mods you are doing. It is a very interesting science (at least Bob and I think so, LOL). Is that the geek side of the dark side?
Lloyd-ss

[alex77147]

That's excellent power at 1750 psi.... How many shots are you getting per fill, and from what size tank?.... Are you running regulated or not?....

Bob

Bob, Those shots were taken with a 2260 tube and a bored out disco valve so i'm not sure on the total volume and the gun at the moment is not regulated.  There is no gauge block so according to my benjamin hand pump I filled it up to 1750psi and I don't know what the pressure dropped to after taking a shot since I don't have a gauge yet.  As far as shots go I get about 5 shots above 40 fpe with the disco spring.  I will be running regulated though, I'm still trying to decide how I want to do it though and still testing for what pressure I should set the regulator(I'm leaning towards 1500-1600psi).

[alex77147]

Alex,
That sort of inverted bathtub velocity curve is to be expected.  Because the seat of the valve has been drilled out, it has more force from the air holding it shut.  [Force (in pounds) holding the valve shut = psi x area of the valve throat in sq ins]  Therefore, the stock disco spring has a harder time opening the valve when is has full pressure in it.  As the pressure drops with each shot, it is easier for the spring and hammer to open the valve so the velocity starts rising.  Then as the pressure continues to drop the velocity will start to fall off. 
Basically, drilling out the valve seat (throat) shifts the peak of the velocity curve to a lower pressure, in the same way that installing a weaker spring does. 
You have persevered and are doing excellent work. (YEA!) Keep good records and plot the data in excel like Bob does.  After you plot the data for different set-ups you will start being able to predict what results certain changes might produce and will gain an understanding of cause and effect with the mods you are doing. It is a very interesting science (at least Bob and I think so, LOL). Is that the geek side of the dark side?
Lloyd-ss

Yes Lloyd I did expect it, but if you remember after i'm done tinkering with this thing it will be regulated and so I won't have to worry about the curve.  And thanks for your help with the valve

[rsterne]

In order to keep similar power levels once regulated, I would suggest you use the entire 2260 tube as a plenum downstream of the regulator, so the only basic difference you will have is that the air pressure in the tube is constant.... That way you can be pretty sure your power won't drop from lack of volume to feed the valve....

Bob

[alex77147]

In order to keep similar power levels once regulated, I would suggest you use the entire 2260 tube as a plenum downstream of the regulator, so the only basic difference you will have is that the air pressure in the tube is constant.... That way you can be pretty sure your power won't drop from lack of volume to feed the valve....

Bob

Like what you did with your 2260? I currently have a 48ci tank and a remote line but I have a low profile myth regulator and it isn't adjustable much.  So I will be needing a new tank since a new reg is almost as much as tank with a reg.  I'm thinking maybe ill use a 22/13ci tank and make a new stock and have the tank as the shoulder stock and run the remote line to the tube, but that might not look as clean as yours.

[rsterne]

All I'm suggesting is that you don't chop off the tube short and reduce the volume between the regulator and the valve.... HOW you do it is totally up to you....

Bob

[alex77147]

Understood