another 22xx valve test only this time I modified…
…the Mountain Airguns modified Crosman valve along the lines of Walters recommendations (countersunk transfer port)
Please keep in mind that I am not an engineer, nor a machinist…so please have patience with my “laymans” terms and methods…
The Mountain Air valve performed in the previous test as follows:
CP 14.3 72degrees 15 seconds between shots 14″ barrel 12gr cart gun
561 559 555 557 561 569 563 565 567 565 555 559 553 549 546
new #’s with coutersink valve mod, slightly different TP tubing material, and 15 degree warmer temperature…all else was the same with the gun used in the first test.
592 594 601 604 613 610 607 600 606 609 605 612 615 616 606 609 608 600 584
These numbers are much better and I I don’t know if the hotter temperature could have affected the test results…it is my understanding that co2 is more “pressurised” at higher temps…(please chime in on how many fps a difference of say 13 degrees would be????)
Anyway, it was around 85 and my co2 carts have been sitting in a hot garage with temps near 93 degrees these last few days.
Here is what I did:
I simply took a 7/32″ drill bit and opened up the tp hole a little more than it already was. I took a 1/4″ (grinded the drill bit flat {as suggested by Walt) and then countersunk the Transfer port by around .115″ (sorry, I forgot to take pictures of the valve after I did it…)
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The tubing that I used for this test was different than the rigid AC custom tubing (only because it fit my 1/4″ coutersunk hole tighter than the AC custom did…) It is the clear tubing pictured. The measurements are very close to AC’s tubing (.247 od .165 id)
Here are a few pictures of how the carbine looks as a pistol:
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So the question is would the counter sinking of the transfer port tubing into both the valve and the barrel create a more efficient flow of co2 (none wasted in the frame, etc) to account for that large increase in FPS? I am guessing yes, and since Walt runs his 22xx with countersunk tp’s…I think I will do this mod to all my 22xx valves!
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Viewing 9 replies - 1 through 9 (of 9 total)
Joe,
I also think you might should post this mod on the Crosman Air Pistol Owners Forum. I think there are a bunch there that would appreciate what you’ve found out and what you are working on.
Carl
Good choice on the Mother’s Day gift. I know she will appreciate your thoughts. 🙂
Carl,
Nothing special about it. The hard white (opaque) is what I received from alejandro from AC custom parts. It came with one of his barrels and Transfer Port Mods…very nice work he does…Perhaps you can write him to get his take on it.
I started out by looking for the “kids straws” from Pizza Hut as suggested by Walt…but the Pizza Hut in my town closed down due to Roach and Mice infestation…LOVELY 😯 Anyway, I had the tp material from Alejandro and the other clear stuff is from either my aquarium stuff or gasoline stuff (not sure which). The black stuff I don’t have a clue to its origins…it was in my toolbox.
Packrat,
Your welcome. I am curious to see what you think about it when you install some in your project.
p.s.
I was going to buy my wife an Air Ranger for Mother’s day, but I decided on Flowers and Chocolates instead 😀
So, what’s so special about this tubing you two are using for the transport tube? It sort of looks like some I have laying around but would help if I had your personal descriptions.
Carl
Okay packrat, I’m gonna see if I can find Mom a complete CNC setup for less than a $1000 and delivery tomorrow. 🙂
Joe- the gun I got from MA has the HUGE tubing you talked about!!!
BTW THANKS for the tubing–got it in today’s mail…I’m liking the looks of it….gonna do some experimenting with it as soon as I finish the 17/22/2078/disco project..all I need is the new Crooked Barn Ultimate bolt and I can put it together and go a’shootin’ 😀
thanks again!
well hell MOther’s Day is HERE !!! go out and buy that dear lady a complete set-up CNC…evrything!!!
I am reworking my box stock 2240 now and this kind of information is really useful. Thanks 80grit and packrat for posting this stuff.
I will be playing around with the transfer ports week after next. Can’t start next week as my mother is expecting me to spend a week with her and she has no machine shop. LoL
Carl
I don’t have exact numbers as far as fps gains using CO2 in warmer temps, but I do know that it can make a significant difference, wish I had definitive numbers for you, sorry… Last time I did a shot string with my 2250.before converting to HPA, here’s the results I got…Alpha Cnrony…..
704-699-681-672-667-665-668-670-679-675 14.3 Crosman HP’s, 80 degrees, power adluster out 1/4 turn from coil bind, Disco hammer spring, new Crosman cartridge..18″ inch barrel.
Those are some good numbers packrat!
The TP material I am using is not from Roy. The piece of “aquarium” tubing that came with his 2250 pistol (which I bought used on the Yellow)
meausred .277 od and .170 id. Also, I bought one of his 2550 with a LW 24″ barrel and that tubing was huge: .353″ od .250″ id. These were flat on the bottom (melted) to sit flush against the flat valve face. Is this how yours were from him?
Anyway, Walter stressed that by countersinking you eliminate excess stress on the breech screw…and when you look at the countersunk tubing in the valve as well as the barrel…it just makes sense to do it this way for the most efficient flow with the least amount of lost/wasted gas.
I am going to instal a hammer debounce device (HDD) as many have said it will increase shot count. Although I cannot hear any “hammer bounce”…I am not too sure it can be heard??? But I do notice a large plume of gas exiting the muzzle…so perhaps the HDD will help. Lord knows I would like to get more than 16 to 20 shots on a cart.
My stainless pistol is coming along nicely. I am building this one as a cart gun as well. I have other pcp’s in the works…but this one will be a 2260 on carts. I will post pics when it is done.
That’s sorta strange…my Mountain Air 2250B had the .250 ” poly tube in TP when I got it..I wonder at what point Roy started doing that?? Joe, how old is the gun you’re working on?? I bought mine in December of ’09..so I know he was using the the poly tube at that time……..
I don’t have exact numbers as far as fps gains using CO2 in warmer temps, but I do know that it can make a significant difference, wish I had definitive numbers for you, sorry… Last time I did a shot string with my 2250.before converting to HPA, here’s the results I got…Alpha Cnrony…..
704-699-681-672-667-665-668-670-679-675 14.3 Crosman HP’s, 80 degrees, power adluster out 1/4 turn from coil bind, Disco hammer spring, new Crosman cartridge..18″ inch barrel.
Viewing 9 replies - 1 through 9 (of 9 total)
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Quickster…this NOT a new thing, guys have been using varieties of this for long time..In fact, Brutuz, even has some he was giving away to anyone that wanted to try it (you have to pay shipping).. But, it does appear that more and more types/sizes of tubing are becoming known.. there’s even one called the CLPS (can’t leak port seal) someone came up with, and it does look like it would work great..I just haven’t taken the time to see what gains are possible using this stuff..but I am going to MAKE time for it, as soon as I finish the current project 🙂