I have an Impact .25 I'm trying to tune for tighter groups at distance. I'm finding a slower velocity is helping with groups. My question is: When does one use the valve adjustment? I mean I can adjust the power wheel but how does the valve setting come into play? Is it better to go with a high power wheel wheel setting and drop or increase the valve to achieve desired velocity? I've just never been able to wrap my head around this. Hoping the tuners can chime in here. Right now I am at Max on the power wheel and have rolled the valve down close to 3 line for a speed of 830 fps. Groups are tightening up at around 65 Yards. Looking to understand the relationship between the powerwheel and the valve adjust. Thanks
Please help me to understand.
- Thread starter Drumsnguns
- Start date
Drumsnguns
The valve adjustment is used to adjust how long the valve stays open after the hammer strikes it. It can also be helpful for conserving air usage.
eg: I was pushing the big fat 50gr .30 cal pellets out at 904fps (MAX!). Hammer setting was max, regulator was down around 100(IIRC), but my valve adjustment was waaaaay out (almost to the point of falling off)! I was experimenting when I did this and would not recommend these settings. The air consumption was awful since the valve adjustment was so far out. But, the valve stayed open so long that it just kept pumping air down the barrel accelerating the pellet.
Here's what I recommend....
Start a journal with your factory settings, include pictures. Read this thread as well for tips and tricks.
Leave that valve adjuster between 3-4. Find the pellet you want to use. Adjust your power wheel until you get close to your speed. Adjust your valve setting to fine tune your speed.
Through lots of experimenting, I found that my Impact liked power setting #4 best. It shot smooth and consistent. So, I tried to adjust the valve setting to attain my desired speed.
The Impact has so many ways to adjust that a person could do nothing but adjustments without ever really taking it out to shoot at anything! Consider the power wheel, power wheel trim, valve adjust, regulator, pellet size (not caliber), pellet weight, Pellet caliber.
All of these adjustments and variations affect the overall performance of the rifle. There is an intimate relationship between the bottle pressure, regulator setting, power setting, and valve setting. When you adjust one, it affects another in some way. The trick is to find the settings where everything is getting along with everything else. Then, stars will align, zen will be realized, yin and yang, and every pellet will find the bull.
Tom
The valve adjustment is used to adjust how long the valve stays open after the hammer strikes it. It can also be helpful for conserving air usage.
eg: I was pushing the big fat 50gr .30 cal pellets out at 904fps (MAX!). Hammer setting was max, regulator was down around 100(IIRC), but my valve adjustment was waaaaay out (almost to the point of falling off)! I was experimenting when I did this and would not recommend these settings. The air consumption was awful since the valve adjustment was so far out. But, the valve stayed open so long that it just kept pumping air down the barrel accelerating the pellet.
Here's what I recommend....
Start a journal with your factory settings, include pictures. Read this thread as well for tips and tricks.
Leave that valve adjuster between 3-4. Find the pellet you want to use. Adjust your power wheel until you get close to your speed. Adjust your valve setting to fine tune your speed.
Through lots of experimenting, I found that my Impact liked power setting #4 best. It shot smooth and consistent. So, I tried to adjust the valve setting to attain my desired speed.
The Impact has so many ways to adjust that a person could do nothing but adjustments without ever really taking it out to shoot at anything! Consider the power wheel, power wheel trim, valve adjust, regulator, pellet size (not caliber), pellet weight, Pellet caliber.
All of these adjustments and variations affect the overall performance of the rifle. There is an intimate relationship between the bottle pressure, regulator setting, power setting, and valve setting. When you adjust one, it affects another in some way. The trick is to find the settings where everything is getting along with everything else. Then, stars will align, zen will be realized, yin and yang, and every pellet will find the bull.
Tom
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Thanks Tom,
But I took some chrony readings with the valve set in at 3 and hammer at max. It goes from 836 on one shot to 805 several shots later. The readings are all over the map. I was just standing there with my mouth open. ES was 31 and SD was 8....this is terrible for a $2K gun. I'm stopping now and trying to decide what to do. Not really happy with the impact at this point. It either goes to Ernest for a thorough going over....not even going to mess with AOA and if that doesn't work then I'll mothball it. Going back to my Cricket....that gun, I enjoy shooting. Oh well.
But I took some chrony readings with the valve set in at 3 and hammer at max. It goes from 836 on one shot to 805 several shots later. The readings are all over the map. I was just standing there with my mouth open. ES was 31 and SD was 8....this is terrible for a $2K gun. I'm stopping now and trying to decide what to do. Not really happy with the impact at this point. It either goes to Ernest for a thorough going over....not even going to mess with AOA and if that doesn't work then I'll mothball it. Going back to my Cricket....that gun, I enjoy shooting. Oh well.
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Your internals are fighting each other, or something else is affecting your numbers. I understand your frustration. Part of the fun of owning an Impact is going through this process. Fun for some, not so fun for others.
When you get back to it, set your hammer to 4 or 3 and check your consistency. Don't worry about fps right away, just look for consistency. If you've messed with the power wheel trim setscrew at all, check to make sure it isn't moving around.
If your rifle is new, it could be that your reg is still settling in.
When you get back to it, set your hammer to 4 or 3 and check your consistency. Don't worry about fps right away, just look for consistency. If you've messed with the power wheel trim setscrew at all, check to make sure it isn't moving around.
If your rifle is new, it could be that your reg is still settling in.
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I had the same problem till I realized that the pellet probe was misaligned I fixed two times already , last time I put super glue, hope it doesn't become loose again, now it is shooting great..
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Tom,
I was set at line 4 on the valve and Max on the power wheel and getting very consistent shots....Ave: 862 fps, ES 9 and SD 2. Groups were good but always getting flyers...at least one with every group,,,,without fail. Funny, at 50 yards an 8 shot group has 7 shots in a group under 0.5" and the one flyer about an inch away .......my latest 100 yard group is over 6". I pulled the valve back to line 3 where I was shooting at 820 and the groups shrank but the chrony number s are all over the place....how can one tune when one shot is 833 and the next is 805. So I tried your suggestion PW setting is 4 and valve is between 3-4 but still getting erratic number, ie no consistency. Something definitely wrong here. I've had the gun since October and have put quite a few tins through it. Pretty sure the reg is broken in and if I'm getting SD 2 at max then that would support that. As soon as you start to use the valve...the velocities just start jumping all over the place.
I've had to run the regulator up to 150 to get 860 fps with everything maxed out. Not worried about killer velocity but just need a little bit of overhead work work with. If it shoots great at 820 with no flyers then that's where it will stay. If 880 is the magic number that others talk about ...then I'm up the proverbial creek with out a paddle.
Eddy when you talk about the probe being out of alignment...are you saying side to side or front to back? Ernest has a video that show the hold down screw can loosen and the probe can be moved side to side of the center line.I know that if in the barrel too far or not enough then it won't line proerly with the TP then that can affect other things. What is yours?
I have a feeling something has come loose with the valve linkage assembly and I'll have to tear in to it.. Appreciate all input, Tom and others.
I was set at line 4 on the valve and Max on the power wheel and getting very consistent shots....Ave: 862 fps, ES 9 and SD 2. Groups were good but always getting flyers...at least one with every group,,,,without fail. Funny, at 50 yards an 8 shot group has 7 shots in a group under 0.5" and the one flyer about an inch away .......my latest 100 yard group is over 6". I pulled the valve back to line 3 where I was shooting at 820 and the groups shrank but the chrony number s are all over the place....how can one tune when one shot is 833 and the next is 805. So I tried your suggestion PW setting is 4 and valve is between 3-4 but still getting erratic number, ie no consistency. Something definitely wrong here. I've had the gun since October and have put quite a few tins through it. Pretty sure the reg is broken in and if I'm getting SD 2 at max then that would support that. As soon as you start to use the valve...the velocities just start jumping all over the place.
I've had to run the regulator up to 150 to get 860 fps with everything maxed out. Not worried about killer velocity but just need a little bit of overhead work work with. If it shoots great at 820 with no flyers then that's where it will stay. If 880 is the magic number that others talk about ...then I'm up the proverbial creek with out a paddle.
Eddy when you talk about the probe being out of alignment...are you saying side to side or front to back? Ernest has a video that show the hold down screw can loosen and the probe can be moved side to side of the center line.I know that if in the barrel too far or not enough then it won't line proerly with the TP then that can affect other things. What is yours?
I have a feeling something has come loose with the valve linkage assembly and I'll have to tear in to it.. Appreciate all input, Tom and others.
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Mine is coming front to back.. and the transfer port doesn't aline with the pellet probe hole..here is a picture 
http://s1259.photobucket.com/user/eurrutiahidalgo/media/5719427B-41CB-458C-96AA-108431EF4DD6_zpsp7i7vtlw.mp4.html
http://s1259.photobucket.com/user/eurrutiahidalgo/media/5719427B-41CB-458C-96AA-108431EF4DD6_zpsp7i7vtlw.mp4.htmlUpvote 0