22xx valve mods

[alex77147]

ok so I disassembled my 22xx hpa.  My intentions were to modify the valve for flow.  I am using a discovery valve.  I need to know what is the largest diameter that I should drill out the transfer port to.  I was wondering if anyone has ever bored out/ drilled the inlet side of the valve if so what drill bit/ diameter so that I could still leave a lip big enough to hold the spring for the stem.  i'm hoping to get 30+fpe after getting the mods done.  Any advice will be helpful, thanks in advance.

[1377x]

it can be done
use the same mods as a 22xx valve
use a heavy hammer spring available here on the forum in the classified section

[run and gun]

i think the max is .05 mm???good question. i bet rstern can anwser that?

[rsterne]

The inlet of the valve is 1/4", and that is the same size as the ID of the spring, so drilling out the inlet won't help because the spring will still be in the way.... The outlet side of the valve is 7/32" with a 5/32" stem inside the hole, so the area of the exhaust throat is the same a a 5/32" hole anyway.... That means that the air can get into the valve a lot faster than it can get out.... Where you CAN get a gain is by increasing the hole in the gauge mounting block.... IIRC, it's only 1/8".... The problem is that there is an O-ring seal for the gauge adapter that is very close to that 1/8" hole.... so I don't think you can just drill it out to 1/4".... I used a milling machine and bored the gauge block out to 5/16" ID but I did it off center (away from the adapter port) and then tapered both ends just to smooth the flow.... I also tapered the valve inlet for the same reason, although I left the hole at 1/4" down by the spring seat.... 

Where you can make a larger gain is on the outlet side of the valve (.22 cal only).... I use a 5/32" mill set at a 20 degree angle to enlarge and smooth out the flow, and then I smooth it further with a 1/8" ball grinder in a Dremel.... I then drill the Crosman transfer port out to 0.161" and the barrel port out to 0.166" (those are numbered drills).... Because the port is so tiny, you pretty much have to use a lathe to hold it and drill it accurately, and go just one size at a time.... When you drill out the barrel port you have to do it one size at a time and make sure it doesn't grab and damage the other side of the rifling.... Then you have to carefully smooth off the inside of the barrel where you enlarged the port ot make sure there are no burrs or sharp edges to damage the pellets during loading.... DON'T do those changes on a .177.... 

The above changes, in conjunction with a heavier hammer spring and a 2400 psi fill, will easily get you to the 30ish FPE level in .22 cal, especially if you use an RVA to adjust the hammer spring preload....  Don't forget, more power = fewer shots....

Bob

[0351_Vet]

Bob,

Would this too Apply on a .25 Cal?

[rsterne]

It depends on how much power you are trying to get.... If you are going for 45+ FPE you might have to go a bit bigger on the ports.... You could drill the valve throat out a bit (I'm not sure if you can get to 1/4", I don't think so) and thin down the stem (I went to 0.115").... grind out the exhaust portion and make sure the corners are smooth and rounded.... You are always limited to the most restricted part.... The barrel port can't be drilled larger than 3/16" (0.188") or the pellet may not load properly, so that is the ultimate limit.... You can't get that big with the stock steel Crosman transfer port, or with the 1/4" OD poly tubing, they both limit you to about 0.161".... I don't think you can easily get the Disco valve ports that large, either....

Having said that, I got my .25 cal Disco up to 58 FPE with 42 gr. EunJins and about 52 FPE with 25 gr. JSB Kings.... The problem is on shot count, so I detuned it to 45 FPE with the JSBs to get 11 shots per fill.... I had bored out the valve to 0.60" ID and cut off a couple threads on the front end (more volume), tapered the intake, bored out and tapered the gauge port, drilled the valve throat and thinned the stem and shortened it 0.060" (to increase hammer travel).... and I managed to get the valve exhaust port ground out to 0.161" and squeaked the transfer port to 0.166".... ie I did just about everything I could think of to the valve.... I was running a Trakar 1.75" x 0.040" wire spring (my heavy Disco spring) backed off 2 turns at 45 FPE.... filling to 2100 and refilling at 1200 (after 11 shots).... 

Lloyd took things a bit further on his twin-tube .25 cal Disco.... especially in the hammer department....

Bob    

[sshewins]

Just askin, but isn't what you're describing be the same as a boss valve?  If so, wouldn't it be easier to just get the boss valve and drop it in?

[MustangMike]

boss valve is not ment for hpa (i think) and the op is using a stock disco valve

[0351_Vet]

Bob,

Great information.....Yes Lloyd has a little rocker there. I will PM or email you when my parts are all together and we'll talk more. (Also about that other January Stuff ) For now it will be cut and paste and digest. Again, that's for taking the time to expand.

Walt

[trekkerx]

You can use B&A`s Boss valve!Ihave two rifles that use them.Both of thse rifles`s have Boss valves in them.The Camo stock with two barrel bands has a heavy spring in it & shoots the 16 gr. Predators at about 1050 for about 14 shots on a 2700 psi fill.

[0351_Vet]

trekkerx....Nice rifles and great shooting boxes (racks). Way cool.
Thanks for sharing and yes, I agree about the Boss Valves.

[MustangMike]

did i read something wrong ? i swear i was just reading about a boss valve being thinner then the disco valve and not having been tested over 1200psi... im sorry i got confused on that..

[trekkerx]

Ron(B&A) Makes two versions of the Boss valve:One is designed for piercing the co2`s powerlet & the other is a modified Disco valve.They are a little different from the stock valves & are made of brass.There are so many parts out there for 22XX that you can pretty much mix & match parts & come up with what ever you want.I mean some parts have to modified for your particular project.Glad you like the pics.The box the rifles are sitting on was made by my father.It`s a cleaning kit with a drawer.He made it out of a tree he cut down in the yard.Not manufactured wood.Well the part that the rifle sits in might be plywood but most of it was cut from a log.

[MustangMike]

i got my posts mixed up, i was doing some reading on the crosman pistol forum and some one had asked about using i thin it was a mellonair valve or something.. my bad, got my info mixed up.. i got to stop trying to multi task, i even almost posted some stuff for work by accident

[alex77147]

The inlet of the valve is 1/4", and that is the same size as the ID of the spring, so drilling out the inlet won't help because the spring will still be in the way.... The outlet side of the valve is 7/32" with a 5/32" stem inside the hole, so the area of the exhaust throat is the same a a 5/32" hole anyway.... That means that the air can get into the valve a lot faster than it can get out.... Where you CAN get a gain is by increasing the hole in the gauge mounting block.... IIRC, it's only 1/8".... The problem is that there is an O-ring seal for the gauge adapter that is very close to that 1/8" hole.... so I don't think you can just drill it out to 1/4".... I used a milling machine and bored the gauge block out to 5/16" ID but I did it off center (away from the adapter port) and then tapered both ends just to smooth the flow.... I also tapered the valve inlet for the same reason, although I left the hole at 1/4" down by the spring seat.... 

Where you can make a larger gain is on the outlet side of the valve (.22 cal only).... I use a 5/32" mill set at a 20 degree angle to enlarge and smooth out the flow, and then I smooth it further with a 1/8" ball grinder in a Dremel.... I then drill the Crosman transfer port out to 0.161" and the barrel port out to 0.166" (those are numbered drills).... Because the port is so tiny, you pretty much have to use a lathe to hold it and drill it accurately, and go just one size at a time.... When you drill out the barrel port you have to do it one size at a time and make sure it doesn't grab and damage the other side of the rifling.... Then you have to carefully smooth off the inside of the barrel where you enlarged the port ot make sure there are no burrs or sharp edges to damage the pellets during loading.... DON'T do those changes on a .177.... 

The above changes, in conjunction with a heavier hammer spring and a 2400 psi fill, will easily get you to the 30ish FPE level in .22 cal, especially if you use an RVA to adjust the hammer spring preload....  Don't forget, more power = fewer shots....

Bob

ok, so I will taper the inlet of the valve, thin out the valve stem, angle the exhaust port.  I got this rifle from a member of this forum, the gun has a 2260 tube and the valve doesn't have any gauge port.  Also the gun came with a poly tube for the transfer port, I dont have the steel transfer port seal.  I want to replace the poly tube when I put the gun back together where can i get the poly tube?  I also have a power adjuster, and I am running about 1300-1400 psi from a regulated 48ci hpa tank, so i'm not worried about shot count.  With that setup the gun made over 20fpe before I installed the power adjuster, after the power adjuster the gun feels more powerful but i'm not sure how much power it makes because I don't have a chrony.

[0351_Vet]

Ron(B&A) Makes two versions of the Boss valve:One is designed for piercing the co2`s powerlet & the other is a modified Disco valve.They are a little different from the stock valves & are made of brass.There are so many parts out there for 22XX that you can pretty much mix & match parts & come up with what ever you want.I mean some parts have to modified for your particular project.Glad you like the pics.The box the rifles are sitting on was made by my father.It`s a cleaning kit with a drawer.He made it out of a tree he cut down in the yard.Not manufactured wood.Well the part that the rifle sits in might be plywood but most of it was cut from a log.

Thanks again trekkerx..........

[rsterne]

At 1400 psi you won't benefit from a heavier hammer spring than the stock Disco spring.... You say you are using a 2260 tube, what spring are you using?.... The wire size on a Disco hammer spring is 0.035" and that is enough for the pressure you are running, particularly if you have an RVA....

Bob

[alex77147]

At 1400 psi you won't benefit from a heavier hammer spring than the stock Disco spring.... You say you are using a 2260 tube, what spring are you using?.... The wire size on a Disco hammer spring is 0.035" and that is enough for the pressure you are running, particularly if you have an RVA....

Bob

I believe all the guts are from a disco except the tube and a 2240 pistol grip, I wish I knew what the guy used before I got it from him.  I have pictures, will you be able to tell just from a picture?

[alex77147]

so where can I get the poly tube, and what size would I need?

[rsterne]

I can't tell the spring from a photo.... Get some cheap digital calipers (how can you live without them anyway?) and measure the wire size.... If it's 0.035" it's from a Disco, 0.032" from a 13XX, and 0.030" from a 22XX.... The Disco spring is the one you want for 1400-1600 psi, especially if you have an RVA.... Don't crank the adjuster to the maximum, play with it to get the best shot count without losing much velocity.... You will find a plateau at the top end where you can keep increasing the spring tension without gaining much velocity, and eventually you will gain none at all.... By that time, you are just wasting air, you want to back off on the spring preload to JUST before the plateau.... That's as good as you can get for velocity without doing other mods or running a higher pressure.... without wasting a ton of air....

Bob