Tuning Fx Impact MK2 springs and Hammers?!?

[Hunter82]

Honestly I am lost in all the options. I understand that the impact has gone through tons of minor changes that are sometimes not documented in a useful way. I have 2 impact Mk2, I would normally do my own experimentation but I just dealt with a damaged Oring sealing surface @ C39 19790 so id rather not take the gun apart another 10 times.

I am trying to tune one gun in .22 to shoot jsb knockouts and leave power on the table to shoot some heavier stuff.....easy. The other gun in .25 to shoot hades on the low end of the power wheel (16 position m3 wheel) and heavyMk2's on the top end. I have 2 stock hammer springs, a ver1? fx slug kit (heavy hammer spring, light valve return spring, 2 hammer weight washers) and a tungsten hammer.

That's the stuff i have, the goals and the backstory.

Is there a rule of thumb for combinations of springs and hammer weights to allow for hammer spring(power wheel) adjustment range for a given regulator pressure?

My .25 is currently shooting MK2 33.95 @970fps, reg 130 , Power wheel 16, 700mm barrel, power plenum, heavy hammer spring(fx slug kit ver1), stock valve return spring, stock hammer 1 washer weight. Hardly any adjustability on the power wheel. My gut is telling me to increase reg pressure to stiffen up the valve.


edit: Basically i am saying that i have a bunch of FX upgrade parts and trying to get 2 pellets to shoot out of one gun with one tune. I got here with the .25 because i dumped a bunch of parts into it all at once when i upgraded my .22. So i am looking for an explanation of how the springs and hammers relate to each other at different regulator pressures. At one point in time Ted was preaching higher reg pressure to use a shorter burst of higher pressure to get more controllable results. This can't apply with different setups..

 

[DanT55]

I updated my Impact MkI with Power plenum and block along with the new hammer spring for the valve and the weight that came with it. I would also check your C1 projection from the frame. 910 tuning has a good vid on this. I installed a Huma 1st reg for the Mk1 set at 140 and my 2nd reg set at 100bar. Also using a Mk3 power wheel set at 8. Barrel is a 600mm Superior with a pin probe. Hitting 890 with 33gr JSB's. SD is around 2 for a full mag. I feel this speed is solid for the 33gr pellets. Your reg pressure maybe a bit high for the hammer weight your using if its a standard.

 

[Hunter82]

I updated my Impact MkI with Power plenum and block along with the new hammer spring for the valve and the weight that came with it. I would also check your C1 projection from the frame. 910 tuning has a good vid on this. I installed a Huma 1st reg for the Mk1 set at 140 and my 2nd reg set at 100bar. Also using a Mk3 power wheel set at 8. Barrel is a 600mm Superior with a pin probe. Hitting 890 with 33gr JSB's. SD is around 2 for a full mag. I feel this speed is solid for the 33gr pellets. Your reg pressure maybe a bit high for the hammer weight your using if its a standard.

Interesting stuff. I left out the details of FPS and accuracy on purpose trying to maintain the focus on adjustability. What i am getting from what you said is : revert the hammer and springs back to stock, and tune the lighter hades on the mid end of the power wheel and hopefully id get 890 to 900ish with the mk2's on max. Side question are you seating past the TP with a pin probe ? "33gr JSB's" = king heavy or king heavy mk2?

 

[DanT55]

Interesting stuff. I left out the details of FPS and accuracy on purpose trying to maintain the focus on adjustability. What i am getting from what you said is : revert the hammer and springs back to stock, and tune the lighter hades on the mid end of the power wheel and hopefully id get 890 to 900ish with the mk2's on max. Side question are you seating past the TP with a pin probe ? "33gr JSB's" = king heavy or king heavy mk2?

Do you have the hammer and spring from the PP kit installed? I would keep them in and try running a lower reg pressure first with Max spring or close to it. Make sure your valve adjuster is out past the last mark or at the last mark. Try tuning from there. Yes, I am sure it is seating past the TP. I have it set up with the dual port for better flow vs the single port.

 

[Bigragu]

swapping in heavier/longer springs in combination with heavier hammer weights that thicken the base of the weight adds preload to the spring. The extra preload, the lighter valve spring, will all give you big and fast power but the deal with the devil on that is you will lose full adjustability of the power wheel.
Before you say I can still get lower powers at lower wheel settings I’m not talking 50 FPS lower than when on max, cause that’s about the best you’ll get with high power mods. If you compare velocity drops on a factory gun with factory parts, 150-200 FPS differences can be had from minimum to max.

These are choices you need to weigh out when upgrading for big power. You cannot have a high power slug set up and with a turn of the knob now have a nighttime high shot count rat gun.

That’s why folks that want both a low velocity 22 cal with high high shot count for night time rat pesting and a high power 90 ft lbs plus 200 yard gun shooting slugs typically invest in two guns and do a set it and forget it.
The scenario I described in the last paragraph is just an example, of choices I’ve seen made over the years

Hopefully on your set up with the lighter valve spring you inserted that black rubber ball within that spring to avoid valve rod over travel when you pull the trigger. You’ll know when you hear a pop by the mag well and you suddenly get a burst of air in your face. Time to take the Gun apart and replace busted o rings on the valve rod

 

[Hunter82]

Do you have the hammer and spring from the PP kit installed? I would keep them in and try running a lower reg pressure first with Max spring or close to it. Make sure your valve adjuster is out past the last mark or at the last mark. Try tuning from there. Yes, I am sure it is seating past the TP. I have it set up with the dual port for better flow vs the single port.

I did the PP720 upgrade to the .22 full kit with the polished block. The .25 got the leftovers from the PPMk2 ill have to compare the 2 springs. It is rare for me to have both guns apart at the same time. I always do my initial tune with my valve adjuster at the 4th line (open). Good to know about the Pin probe, hard to get good answers about that because with pellets you are pushing inside the skirt and that varies greatly with each pellet type.

 

[Hunter82]

swapping in heavier/longer springs in combination with heavier hammer weights that thicken the base of the weight adds preload to the spring. The extra preload, the lighter valve spring, will all give you big and fast power but the deal with the devil on that is you will lose full adjustability of the power wheel.
Before you say I can still get lower powers at lower wheel settings I’m not talking 50 FPS lower than when on max, cause that’s about the best you’ll get with high power mods. If you compare velocity drops on a factory gun with factory parts, 150-200 FPS differences can be had from minimum to max.

These are choices you need to weigh out when upgrading for big power. You cannot have a high power slug set up and with a turn of the knob now have a nighttime high shot count rat gun.

That’s why folks that want both a low velocity 22 cal with high high shot count for night time rat pesting and a high power 90 ft lbs plus 200 yard gun shooting slugs typically invest in two guns and do a set it and forget it.
The scenario I described in the last paragraph is just an example, of choices I’ve seen made over the years

Hopefully on your set up with the lighter valve spring you inserted that black rubber ball within that spring to avoid valve rod over travel when you pull the trigger. You’ll know when you hear a pop by the mag well and you suddenly get a burst of air in your face. Time to take the Gun apart and replace busted o rings on the valve rod

I have heard that before and it makes sense to me. It is good to see you mention an FPS range. Most things i have seen/read only talk about the lack of adjustability not how much. With the .25 i am planning on using pellets so there is no need to tap into all the "devils power" Dan suggested 890fps, which when paired with your comment makes me think my FPS range shouldn't be as wide as i initially thought. I was thinking like 950 tops for the 33.95Mk2. I will probably go back to stock hammer and spring setup first, then if i needed/wanted more fps (out side of reg adjustment) ill start making changes.

 

[Vetmx]

Everything Bigragu said is spot on. You are just another victim of pimping an Impact with every hot rod part you can find. Your only shot at achieving what you want, and you only partially will because one tune will be on and the other will be jacked up, is to use a bone stock gun. With that 700mm barrel, a stock Impact will give you all the speed parameters you will ever need.

 

[Hunter82]

Vetmx you offend me sir... hot rod...pimping ... I'd post a picture but it would only help your point. Lol, honestly though I have 2 impacts and I add upgrades on the. 22 slug gun for one reason or another. The old parts migrate to my 2nd older impact.

 

[Vetmx]

Pimp away on the exterior. But you have all you’ll need internally with a stock gun to reach realistic goals at realistic accurate pellet speeds. I have three M3’s. Two bullet shooters and one pellet shooter. My one .25 is a nasty wicked SOB and only has one internal mod for power. Dual tunes for these guns are difficult. Especially if your projectile weights are far apart. My .25 pellet shooter is set to cover 3 pellet weights. All on a good tune because I never touch a wheel or knob. But my three pellet weights are 25, 27 and 28 grains. Speeds are different with them but they all are in a happy spot speed wise and I’m not wasting air or have the gun dumbed down with the wheel.