more results from my 22xx valve comparisons…
testing three valves:
MA (Roy) modified stock Crosman valve
Boss Valve
Discovery Valve
So far I have only tested the MA and the Boss (the Disco will be next)
In all fairness to Roy’s valve, this is not being tested in a gun built by him, so one cannot truly scruitinize it’s performance. It is merely a “part” taken from the “whole” that was his vision and intention. When I received the gun that was “possibly” built by him, the TP was old and the gun had a few leaks…The TP was of the aquarium tubing variety. From the looks of how it performed in a cart gun, and from the looks and sound of the co2 it wasted each shot…I can’t help but think Roy built this valve for a “bulk fill” gun. I am no pro, so please chime in if you have any deductions…, but for some reason the valve remained open for too long when shooting with the MA valve as opposed to the Boss valve. A poor shot count was the result.
Here are a few of the measurements (differences) between the 3 valves
the valve body port opening measurments:
0.1575 Boss
0.1535 Disco
0.198 MA
The MA is much larger than the others (I suspect too large to enable ideal back pressure to close the valve …perhaps I will try a stiffer spring in the future on this valve)
Everything else in this test was equal. The gun is a 14″ Crosman 2250 on 12 gr carts. The TP is poly tubing from Alejandro (AC custom parts–for those who don’t know him, he does great work!)
The measurments on his tubing are:
0.193 id
0.239 od
0.037 wall thickness
Again, the only difference in each test was the valve bodies (the internals were shared).
73 degrees, 14″ barrel, 14.3 gr CP’s, 15 seconds between shots
First test MA valve
558
561
559
555
557
561
569
563
565
567
565
555
559
553
549
546
536
As expected by the sound of wasted gas, and the extreme “muzzle blast” …this shot count was way too low.
The Boss valve performed much better in this “cart” gun (I will test them both again in the near future in bulk filled guns to see how they do. I also want to try Roy’s valve out again with a stiffer valve spring…)
Boss Valve
561
573
581
582
580
573
575
576
570
569
572
569
570
570
573
572
573
566
565
575
576
578
580
579
572
559
After shot 26 it dropped fast. Not too bad, and ES of 21 and a high fpe of over 10.5 and 26 usable shots!
I will test the Disco valve the next chance I get and post pics of my latest carbine called: “Drilled & Filled” . For any old school Hot Rodders out there…you may have an idea on how this one will look 😎 It’s way past my bed time…Good night!
All Replies
80 Grit,
I not modifying those valves, right now, but this is a learning experience reading your work and what Walter chimes in with when you ask him questions.
And at the same time, I think a lot of this information holds true for other valves like the Air Force valves in how they work.
I just took off my first valve and modified it last week after months of reading, I followed closely what I read on the forum here, and the task that I performed while a simple one, was easy.
Knowledge is power, it is all good.
Thanks for sharing all of this with us
Roachcreek
Most interesting information and quite pertinent to my beginning to modify one of my own 2240 valves for just a little more oomph.
Thanks for posting this stuff.
Carl
Thanks Carl, but make sure you don’t listen too much to what I say…rather, listen to the gurus who “chime in” and lend direction…without them I’d be a white flag flapping in the wind 😆
80,
Most interesting information and quite pertinent to my beginning to modify one of my own 2240 valves for just a little more oomph.
Thanks for posting this stuff.
Carl
Thanks Walt! The valve spring that was in it came from Roy’s modified Crosman valve. I have no way of knowing if it is a stock crosman valve spring, or other…The Boss valve I bought was only the valve body. I have some parts set to arrive this week…so hopefully I can do more building and testing. Talk to you later.
80 Grit
Tbanks Walt, so will a heavier spring help close it faster??
closing forces come from the valve spring plus the ‘sail’ effect of the valve head in the valve body. So a reduced margin around the valve head will assist it closing while in the flow of gas.
So to increase the closing force from the sail you can sleeve the body or adjust closing force as you indicate by a stronger valve spring.
Do the spring first and see what that gets you.
Boss valves that I have seen had pathetic valve springs in them.
Tbanks Walt, so will a heavier spring help close it faster??
80, back pressure will hold a valve open NOT close it.
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Voltar_1 said “boss valves I have seen had pathetic valve springs in them”
Pathetic in what respect(s)…too long/short? too weak/too strong? wrong gauge wire? please advise, cause I have a bunch of springs I can use 😀 😀 thanks!