Anyone have a source for these? I have an impulse that will not chrono unless the LPR is set to ~100 PSI and suspect it has a HP core spring. Confirmed with multiple LPRs, valves,dwell settings, hammers, etc.
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Okay, so just to be clear here, the solenoid core spring is NOT your issue.
Both the ICD B2k and the SP Impulse used the Skinner/Parker K4H01 Solenoid, but smart parts modified the core so that it could handle the higher operating pressures of a non-LPR equip Impulse (approximately 180-200 PSI) The modified core spring is ONLY there to keep the the solenoid from venting at approximately 115 PSI (which is where the an unmodified Parker K4H01 will vent).
ALL impulses have the modified "HP" core spring. These solenoids still cycle fine at just about anything over 60 PSI if the rest of the impulse is tuned correctly. The only thing swapping the core spring will do is cause your solenoid to vent at 115 PSI instead of the much higher 200ish PSI.
Have you tried swapping the bolt? It might have swelled up and be causing drag. I know you switched out the hammer, but how does your ram shaft look? Have you rebuilt the ram housing recently? Could be the wrong durometer "o" ring in the housing causing too much drag.
Have you cleaned out the solenoid? It could just be gummed up and sticking. (This is would be my bet honestly). I would clean it thoroughly with q-tips and rubbing alcohol, and VERY lightly relube it with super lube multipurpose grease. It might just be worn out/failing too unfortunately, in which case you will need a new noid.
What is your HPR set to? If your HPR is set way too high then the ram and hammer are going to need WAY more force to open it, hence the higher LPR pressure.
What valve specifically are you using? Have you tried swapping to a weak valve spring?
Do you have a different board you can test? It might be an issue with a capacitor going on the board too.Last edited by Myrkul; 04-21-2026, 01:09 PM.Comment
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Valve: NDZ Rip Valve. No valve spring installed same result with stock valve (just needed a bit more HPR PSI to chrono)
HPR: 170 PSI PE SL3
Velocity: 335-340 FPS on reball FreakXL .675 insert
Bolt: Oring modded voodoo bolt with LV1 Soft Tip. Near zero bolt drag. Had same result with other unmodded stock bolts
Ram: rebuilt stock housing with NDZ shaft. PE hammer, had same result with NDZ rathole (but that was with the stock valve). Used 70 duro buna throughout. Aged urethane had the same result
LPR: Shocktech FGP with ATTKTX Low pressure kit. Same result with stock internals AND Smart parts LPR (smart parts lpr just recharges worse). Same result with LPR on valve cap vs VASA (recharges faster on VASA).
Dwell: 7, same result on 10 (just 5 fps more)
Board: WAS, latest firmware. Have a scifi I have not tested yet.
The low pressure chamber screen was removed (and the chamber was verified to be clean and free of debris)
I have NOT cleaned and re-greased the noid. Ram does get stuck forward when LPR pressure is around 110.
I do have a new noid from airsoldier that I have not installed yet (ICD marked, they claim it works on Impulses with a LPR)Last edited by deadmeat3344; 04-21-2026, 03:31 PM.Comment
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The noid is almost definitely either sticking or failing if it won't Chrono at all until the LPR is at 100 and then it's shooting that hot when it starts working. You might want to drop your HPR pressure a bit if of it only shoots that high.
The ASP noid will work perfectly as long as you keep the LPR below 115. Around 115-125 it will start to bleed off unless you swap the springs over from your current noid. If it was me I'd clean the noid really well. Be sure to get the channel in the gasket on the white disk with a toothpick, grease can build up in there and that can definitely cause sticking.
I don't think I've seen a Eclipse hammer before do you have a picture?
Imo you are right not to use the rat hole. That looks way too light.
Way back when I was building impulses I found that the key to getting them to work well at lower LPR settings was to go heavier on the hammer, not lighter. The hammer I ended up enjoying the most was a big old heavy brass one, can't remember who made it. I was able to drop the LPR quite a bit using that and a NDZ slick shaft with the NDZ valve.
If I were you I'd clean the noid super well, probably set the dwell to 10ms to help with consistency, set the HPR to 150 or so, grab the heaviest hammer you can find, and then adjust the velocity via the LPR.
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Just as a clarification on the reball velocity it will shoot below that. I got that reference off of docfire's reball vs real paint vid and shooting for 335 has netted me around 300 with real paint.
I will service and/or replace the noid with the ASP noid.The eclipse hammer is similar in weight and shape to the NDZ solid stainless. I dont have my pics off hand of the hammer and weight on my scale.
I also have a shocktech brass hammer lying around. I will be swapping the board as well as I was doing that anyways.
Thank you for the help.Comment
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Took the noid apart and verified it was pristine clean.
It was also dry as a bone. Zero evidence of lube.Orings looked fine (or square rings, whatever is on there). Lubed up the spool with some PE grease and now its shooting at around 70/75 PSI LPR with the current Ram/hammer setup.Going to swap in the noid from ASP still since I already have it. LPR drops around only 10 PSI when ramping at 13 bps now.
Going to swap in the scifi and experiment with the lower tube config.
Thanks for the help!Comment
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Awesome!
I would probably just leave the ASP noid in the sealed baggie so it's still NOS until this one actually starts failing for real and doesn't just need light service. These parker noids are seriously built like tanks, I won't be surprised if at least a few of them last longer then I do 😂. -
The noid starting sticking again so I swapped in the noid from ASP. Gained 8 fps and was able to drop LPR down to 50 with the rathole (still have heavier hammers around I can mess with). Swapped in scifi and the gun shot like butter at Splatterpark yesterday at nxl 10.3 with zero shootdown. Ate gas though, dwell is at 10 but Im sure I can drop that now with the new noid.Last edited by deadmeat3344; 04-29-2026, 03:21 PM. -
Ya, it looks like the old noid was just tired I think you might still be able to get it on its feet if you fuss with it enough, but if you already have the new one in there you can save the old one for parts. Glad it's working now!
I don't know if there is much to be gained from switching to a heavier hammer at this point, 50 PSI about as low as I've ever been able to get these noids to work consistently at. They would function at lower pressures, but the velocity got kind of irradic, at least it did on my B2Ks.
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