FX impact valve control knob question
- Thread starter johnp
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The valve works in conjunction with the regulator pressure & hammer spring.
If you're shooting .30 the reg pressure should be between 130-140, the power wheel (hammer) should be 5 or Max, the valve should be 3-4 hash marks.
If the valve is too far open you'll just waste air. Set the reg & power wheel, then back off the valve until you start to see a decrease in fps. That's the minimum setting for the valve based on the hammer & reg pressure.
If you're shooting .30 the reg pressure should be between 130-140, the power wheel (hammer) should be 5 or Max, the valve should be 3-4 hash marks.
If the valve is too far open you'll just waste air. Set the reg & power wheel, then back off the valve until you start to see a decrease in fps. That's the minimum setting for the valve based on the hammer & reg pressure.
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why is the lines are black? is this the newer version ? or is this the uk version ? is it stronger ?
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so that means, you should max out the wheel and the reg and then start gradually reduce the valve??
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I generally start tuning with the valve adjuster opened up to line 4 or just a tad more. I choose a reg pressure and tune to that reg pressure with the macro wheel a cpl notches below max. I tune the optimal spot for the chosen reg pressure a cpl clicks below max so I can up the hammer spring when the gun has sat for awhile to over come the first slower shot phenomenon. With the big dial set a couple clicks below max I back the micro adjuster off quite a bit. I then start shooting over the chrono and slowly working the micro adjuster up until no more velocity increase is seen. Then slowly work the valve adjuster in while still shooting over the chrono. Turn it in until the velocity drops a little bit, maybe 10-15 fps. At this spot you should get good consistency and efficiency. If it isn’t the velocity you wanted then you have to adjust the reg and micro accordingly to get there. Just remember to make small adjustments when doing all this so as to not over shoot the sweet spot. I have a mk2 700 mm and only shoot 44.75 pellets. My reg is 107-108 bar and that shoots them in the low 870’s to mid 880’s. I could work on it a bit more to tighten the ES up a bit but out to 75 yards I have shot it the accuracy is stellar.
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i have an mk2 with m3 plenum and heavy hammer and spring. its a short 500mm barrel with 1:19 and no slug pin probe. I saw a youtube video on short barrel harmonic tuning where they said, with a short barrel you should have a quick burst of air, contrary to a long barrel where you can to the opposite. whats your thoughts on that?
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With a large plenum and a long barrel high reg pressures are not needed. Now with you having a 500 mm barrel you will have to run a higher reg. I’m not really sure how high as that will be a guessing game. You will probably need up around 125-130 bar. I should have added to my post that my mk2 has the bigger m2 plenum. The one I believe is just slightly smaller than the m3 but much bigger than the little original one. Also the internals (springs and hammer) are all stock. You will struggle to run lower reg pressures when you start putting heavy hammers and springs in the gun.
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yes when having heavy hammer and spring its a bit difficult to run lower pressures, i forgot to mention i have the 720cc plenum, and at 140 bar the 25 grains slugs only fly at about 910 fps so i have to spice it up a bit.
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Open the valve adjuster to imaginary 6th line or wide open.. Crank the hammer and micro till the hammer wheel just barely move.. Run the rifle over a chrony and use the valve adjuster to knock 10-15 fps off the top speed..
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Quickest valve closing... Bigger range of adjustments to suit the projectile and no waste of air..
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i thought that the quickest valve closing is when u dont have the knock very much open and you have the reg wide open...Im considering to get a 700 mm barrel since short barrels are ideal for shooting up to 150 yards max....right??
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yes but with 700mm barrel propably, mine is the 500.My MK2 compat came at 85 bar shootinig 44 gr at 840.
wait wait, only 85 bar reg at compact?Valve adjuster full open? tell me your settings please.
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It's more efficient to use the higher bar setting and use the hammer spring and valve control together to get a shorter burst of high pressure vs a longer burst of lower pressure and longer dwell time
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yes i totally get the whole idea, but im struggling brother for the right setting the last weeks...I have an mk2 impact compact which has the m3 plenum and the heavy hammer and spring...i tried apolo slugs 25 gr and with 150 reg pressure (i have only one reg) and it seems i cant get past 950 fps. Many mates told me that its shooting low fps for that setting...
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I'm shooting.22 cal 30 gr cast slugs at around 920 with only 118 bar regulator setting. It's a 600mm barrel MK2 impact.
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