GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: imadunatic on February 10, 2017, 08:45:54 PM
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So, santa in the brown suit brought all my goodies today (grip frames were apparently backordered for 14 minutes???), anyways, this is the first time I've gotten my hands on a discovery valve, and my word is the poppet spring stout; much stouter than I think I want in my 2400KT nylon/aluminum hybrid-hammered, 900 (maybe) PSI HPA conversion.
What is everyone else doing? Can I rob the stock poppet spring out of the stock valve and use that? Can I mate the disco front end to the 22xx back end with 22xx back end and internal parts? This will be just like my other builds, low pressure, lowish energy (looking for 18ish FPE out of the .177), easy breathing and above almost all else, efficient.
I've looked at the other builds, I've gather some ideas, but this stiff poppet spring threw me for a loop.
As always, thanks in advance.
Kevin
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You can use the stock spring in the Disco valve. Depending on what your after you can also do a ton to the Disco valve to make it really breathe. Open and angle the exhaust port, throat can be opened up, threads cut off the valve front. A lot of similar to the 22xx valve mods. I can send you some of my notes from a stock front to an extended front. Bob (Rsterne) was kind enough to provide me with some excellent guidance when I started modding my valve, and wanted to duplicate the extended front he had made first for his Disco Double. Anyway, let me know, and I can either post, or IM you the notes, port sizes, etc.
Casey
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I'd like to let it breathe, but I'd like to also have a lightweight hammer with a light hammer spring and I'm thinking the stock disco valve is going to hamper that, all I really need is the extended front end to get beyond the grip screw and seal the tube. This is a lowish pressure conversion, so I'm not worried about pressurizing a non-roll stamped pressure tube.
That all being said, I'll gladly take whatever you have. I prefer to post stuff in the forums so that it's there for all to see if you don't mind. I'm still in the collecting information phase on this build. I probably won't get too carried away until I have it set up to run off the bottle, see how it does in stock trim and then see where I want to go from there.
Are you running the disco hammer spring as well? This is what I'm really trying to avoid.
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I just want to double check that when you say bottled, you are referring to a regulated bottle like a Ninja 13ci with a 850psi output? If so, a light valve spring (and light hammer spring) is a fine choice. If however it will be unregulated, a relatively stiff valve spring will tend to give a longer shot string because it aids the self-regulation characteristics of an unregulated powerplant.
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Jason,
Regulated,ninja-bottled, 900ish PSI (I stacked the new regulator last night, it landed at 900 psi, so that is my starting point).
Would the stock 2240 valve spring work in a disco valve? If not, any insights on what to use in a regulated setup?
This is going to end up similar to your bottled 2240 you built for the kiddos, except I'm using a disco valve.
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Gotcha, since it's going to be regulated, your valve spring can be as light as you want. In fact, you can omit it altogether except it may be difficult to get it to seal at zero pressure if you are filling with a hand pump.
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I have used a stock 22xx valve spring in a bottle regged setup with very good results. As for valve mods, here are a few I did on one of mine, exhaust port was sized 25 cal use, then choked down for the 22 barrel I have while testing. Between the valve mods, port sizes, and a power adjuster / RVA for the hammer spring gives me enough control over the power curve. Not sure if you are going for shot count or power, these specs were for power over shot count for this platform. So here is what I have, and Bob provided me these great specs, I just had to do the work. Can't thank Bob enough, he has provided all of us with assistance and his knowledge.
"I would just hog out a Disco valve, just make sure the air can flow into the valve easier than it can get out.... If you want to get to 100 FPE in .25 cal, you will want to have at least 0.219" (7/32") ports from the barrel back to the throat of the valve (ie transfer and exhaust ports).... The barrel port should be oblong (3/16" W x 1/4" L) to not damage the pellets on loading.... The throat I would make 0.266" (17/64"), and I would use the poppet from an MRod.... You will have to bush the valve stem hole to reduce it to 1/8" to fit the MRod valve stem.... You can just use K&S brass Hobby Tubing for the bushing (glue it into the valve), 5/32" OD x 1/8" ID..."
I followed these dimensions for my platform, but remember you can control the flow into the barrel, and with your lighter hammer, and hammer spring may very well provide a good deal of shots at a set power level and breathe very well.
Casey
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I tried a light valve spring when I switched to Ninja HPA on my 2250 and adjusted the output to 1100 psi. I lost count on shots I got then dumped what ever air was in the bottle. perturbed me off to switched back the OEM. PIA filling from 0 to 3k with a pump!
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Thanks Casey. This won't be a power build, shot count generally takes precedence for me and my 3K scuba! LOL.
Bentong, other than the pumping, did you not like the HPA setup? Around here, it's cold more often than it's not, so I am generally trying to get away from CO2 (though some guns definitely aren't meant for HPA... :D )
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Only hate it when starting from 0 psi when pumping. I now have 2 hpa set ups, a crosman 2250 and Qb79. Both bottles i set the output to 1100 from 850. I added 2 stainless screws on the valve and drop block and added a set screw on top of it. Shooting both's a pleasure and you get plenty shots.
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Not to throw another poker in the fire, but did another ever try or fabricate an adjustable poppet spring adjuster.
Right now there seems to be so many variables between hammer/primary/secondary springs. hammer weight, poppet springs and regulated pressure. I guess it all depends what one is looking for: Plinking, hunting, target or all of the above. I just enjoy modifying, fabricating and testing air guns. Have fun. Bob
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An adjustable valve spring might have some limited value in an unregulated rifle but would serve no useful purpose in a regulated rifle like being discussed in this topic.
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Kevin, I used a stock poppet spring on my last 22xx bottle build, and did the same as Ben and raised the reg pressure to 1200 PSI on mine, still got a ton of shots at a reasonable power level. It does get a bit chilly here too, so I kinda went a little nuts after the first winter that I got into good air guns. Quickly went to the dark side and only go back to CO2 for a few specific guns. Again if you just going for shot count over power, and are still on CO2 carts you can either make or get a valve reducer from Crosman like the one they put in the target pistol valves to reduce wasted gas, choke the transfer port down, and reduce the hammer weight and spring until you reach the self regulating point. The gun will actually then shoot the same speed regardless of temps down to at least freezing, with a significant increase in shot count. Just another way to consider, I again imply went the HPA route and never looked back.
Casey