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Tuning What spring for power increase on impact mk2

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Interested in what your asking also. With a FX Power Plenum is it the spring that came with the kit or did others opt to go with the factory MK11 hammer spring for more power. I remember there was a lot of back and forth when the PP first arrived on the seen. I'm thinking it was the weaker spring for the PP to take advantage of the lower regulated pressure of the PP's plenum but I could be 100% wrong. Seems I remember some discussion on the valve adjuster also. I'd like to get a little more fps out of my MKII PP but I may have to pull the hammer and see what I used for the spring. bubbag, I'm pretty sure the stock Impact used the same spring as the Wildcats and Royale 500's.

Hopefully someone can remember the exacts and chime in. 

Jking
 
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Replaced the new 52 mm hammer spring with the longer old 57 mm spring,

I got a brass hammer weight from ebay,

also replaced the original valve spring to a softer plus added the rubber ball back for a safety.

I did not purchased the slug-power kit but improvised this valve spring from an automotive parts store, I got couple similar dimensions and pick one that fits the OD.

Heavy 7.5 mm porting in a Rear Block and Valve House (up from 6.5 mm), also a 9.2 mm peek Valve Puppet.

Oh, and yes, I polished the Valve Rod and everything that moves along that rod, also a Huma dual port ver.2 (not the latest ver.3).
 
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Yesterday I pulled to inspect the hammer spring in my PP'd 30cal and it was the shorter, assuming the one that came with the kit. Before the velocity was 960fps at 140bar with the HS wheel on max. I replaced that spring with the longer one that came out of the gun originally. Really helped it a LOT? Now at 140bar it gave me 1010 and I did have to back off the small adjusting screw to allow the power wheel to operate from min to max. My regulator had creeped up over night to 152bar so I thought I'd see what velocity that would give me. I believe it was 1040 something and the next two shots as the regulator settle back in were in the 1020's to 1030's which tells me there is more power easily available if needed. 

Waiting on more slugs I decided to tune it down for 44.75 pellets and I ended up at 96bar, on the Min setting and on the second line to get it down to 880fps. Amazing as to all the options the Impact has. 

Jking
 
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Bubbag sorry for the small of topic notice.

BigHun 

all good with these modes you have done but I think that there is a limitation in the diameter of the valve rod poppet you can use .9.2 is too big and is not allow the air to pass any time the valve is opening.For a valve house transfer port opened at 7 mm i am using a 7.5 mm diameter peek valve poppet and can seal perfect .Anything bigger in diameter than 7.5 peek gave me less speed .Did you try it with so big valve poppet?

Bubbag I am not using an fx pp for the moment ( I have the Poland pp) because I have few problems to install it and I need to modify by brass all the tune that is going inside the action , but for the period I have it in my gun I made some experiments with different valve springs that I order from a company.

The lightest power spring gave me crazy speeds but I doubt if I can find it now to give you the dimensions. Anyway for sure you need in the hammer the old type spring 57 mm and you need to test different power springs in the valve adjuster.
 
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