Tuning Baffled by Impact???

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Yup I fergot I had the same thing happen as stotti my hammer seat got loose and I had no power but the valve rod did not break. I was able to remove the hammer seat clean the threads up with a tap as well as the valve rod threads and reinstall it with some blue locktight. Stuck a piece of o-ring, near 1/8th inch long, down the hammer seat before I threaded it on the valve rod. Ernests idea to keep things from coming apart again. I have not had a problem since.
 
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That’s what I’m using too. There are different sized plenums, mine has a 75cc aftermarket plenum, 6.35 valve, hammer weight, a thin delrin C3 bumper, dual port, machined out probe and I’ve got plenty of power in .25. I’m at 120BAR, hammer spring preload about half way, valve adjuster on 3.25 lines and power wheel on Max. Shooting the 33.95gr at 930fps.

When testing a lot of slugs, I had the hammer spring maxed out, valve adjuster wide open and the regulator set on 145 and was shooting the 38.2gr NSA slugs over 1000fps. Like I mentioned in the beginning of this thread, the depth of the hammer seat has a lot to do with max power too. If you crank it down to around 5mm, you’ll gain quite a bit of additional velocity but loose efficiency. 

I haven’t put in the power plenum either, why mess with a good thing. I use the slug A liner with the JSB MKII’s and VK slugs, I don’t think I can make it anymore accurate. I pop in the Superior liner for the FX slugs at 990fps and I can usually shoot under an inch at 100yds with them. When you get these guns dialed in, they’re pretty amazing. And...they look pretty darn sweet, like Glem’s gun!

Stoti
 
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I got the Polish plenum with the higher capacity.

https://www.airgunnation.com/topic/please-post-impact-x-mkii-power-plenum-30-cal-performance/
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That's what I've been using for over a year, I think it's been sorted that its the same volume as the FX ones. Combine that plenum with a bigger valve seat 6.5 or 6.35, hammer weight and delrin c3 bumper and it'll give you the option of fantastic power, shot count or mix of both. I suggest keeping the rest the same.
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👍 Right on Glem!
 
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Months ago when it was announced first time I wanted to buy that slug power kit but non were available for weeks so I finally just removed myself from the waiting list and collected the bits and pieces on my own.

I just replaced the valve spring to a thinner/softer wire (but added a rubber ball for safety), also replaced the hammer spring to 57mm.

Hammer weight is a stock (but eventually I will replace it with a brass piece, I will ask around what is a spec on the heavier hammer weight?), a stock Huma kit (I did not modified yet the dual port and probe). {The very first dual port when I got from Huma I did the increased porting but at that time I was missing a stronger hammer spring and the heavier hammer weight.}

MK2 PP 700 STX liner, .25 JSB 33.9 gr 119 bar gives me 960 max lowered for ES to 918 fps. A big slack on the power wheel slider and the valve is about 4th line I suspect the seat is not touching the rubber ball but next time I am around I will check if any footprint.

Waiting again for months from AGS, ordered the Rear Block + Valve House + Valve Rod, ones all parts in my hands my plan is to go towards a 7mm transfer port (or better an oval = sideways slotted port 6.5x9)
 
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That damn RUBBER BALL!!!

Well, I figured it out and feel kinda dumb but also misled. So in my FX slug power kit are a lighter valve spring and little rubber ball. So after watching Ernest’s video TWICE, I decide to replace the stock valve spring first to see what the effect is. Unscrew adjuster. Remove spring. Insert lighter spring. And, as is directed in the video, I insert the rubber ball. Install adjuster. 600 FPS, a reduction of 350. Huh? Remove lighter spring and install stock spring. 
And here’s my mistake. I left the rubber ball in. So after assemble, still have the very low power. Double Huh???
Today I removed stock spring and rubber ball, and installed lighter valve spring. No rubber ball! And now my speed is 30 FPS more than it was prior to this whole debacle. From 960 to 990 FPS with NSA 36.3 grain slugs. 
Guess I don’t need the dreaded rubber ball?
 
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The rubber ball is there for safety only like a limiter,

I am not sure what is a total stroke length on the valve rod, speculating only,

with a softer valve spring we don't want to have a touch metal on metal with valve stop (A17)...

but also, we need to make sure the other end of the valve rod not to exit the hole inside the valve housing neither...the small oring may not survive...
 
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Mike...I pointed that out in my first post. LOL Glad you fixed it! 

Stoti
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Yes. You did say that and it got me thinking. But you said make sure I don’t have two rubber balls. My stock set up had zero rubber balls. That’s why it didn’t dawn on me because after I inserted the rubber ball there was only one, as directed by Ernest?

I took the valve adjuster off and unscrewed the piece the valve adjuster screws into. No original balls. Where would it be hiding? Could it be stuck in the valve adjuster cap?

On a good note, I have the NSA 43.5 grain slugs at 895 FPS now with reg at approx 128 to 130 bar. No additional hammer weight and stock 52mm hammer spring. Need to check accuracy this weekend but that speed with a high BC approx 0.115, should be good out to 300 yards. If it’s MOA at 100 yards I’m good to go. Ballistically I see no real benefit into bumping up the speed to 950 or higher. Plus the gun is very mild now even at 78 FPE. Higher could cause harshness and make the gun more difficult to shoot accurately. 
 
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The original ball should be jammed in the cap, that’s where it belongs. It doesn’t move freely like the kit’s rubber ball. 

Stoti
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Thanks much Stoti! Ok cool. I looked in there and there’s something flat that doesn’t look anything like a ball. But you must be right since the gun is working good at 78 FPE for the .25 caliber Slug A liner... I bought the gun used, so it could be a ball substitute or something. 
 
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If it’s old and warn, it might be all smashed in there and flattened. Pull it out and reverse it so the round end is facing the valve rod. Unless you’re valve adjuster is on somewhere around 3.5 lines, it wouldn’t even touch the valve rod anyway. You’ll know when you dial the valve adjuster and the velocity drops.

Stoti
 
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He had the original valve ball in the valve adjuster and added the second rubber ball that came with the kit. Both rubber balls would limit the valve stroke by like 3-4mm, hence the 300fps. 

Stoti
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Ah sorry, I missed that second ball somewhere along my writing
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No need to be sorry about anything with me man. It’s all good!

Stoti
 
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