Marauder with .25" PEEK Poppet

[ackuric]

So I decided to tinker some with the poppet on the marauder. I have 2 valves and it is very easy for me to swap each valve and test them side by side with the same spring/tune.

The poppet was made by hand with a dremel. I don't have pics of the process atm but it is VERY simple. DO NOT LET PEEK intimidate you! I also made a peek insert for my striker on the hammer, figured what the heck might as well get my monies worth, this stuff isn't cheap!


Valve 1: .324" poppet and .195" port, stock is about .34". 13 lb spring with pre-load set to 825 FPS. 51.5 FPE

Valve 2: .25" peak poppet with .195" port. Same exact spring/settings as above. 860 FPS. 55.85 FPE

(this valve got ported to .216" because I was feeling wild, but the same .195" tp was used in both tests)

I don't know why I don't listen to my own advice but I went to town on the throat for Valve 2 and efficiency is pretty bad, around 1.2 FPE/CI @ 860 fps, where I have seen efficiency as high as 1.3 at this power. Maybe its not the throat work though... Not gonna pout about it...

Maybe the efficiency is suffering because the valve is so much easier to open, that hammer bounce is showing its face again...such a mystery!

The above info / data is 100% accurate in terms of fps gains...

I just tossed an 11.5 lb spring behind the valve 2 and it is still cranking at 860-870 FPS (56 FPE), where as on valve 1 the most I could get out of this spring was around 47 FPE!!! Wow...

[ackuric]

Hmmm...Mind is boggled

I am hitting 800 FPS / 48 FPE (max) now on my 7.5LB spring that was only good for 30ish FPE Tops with my old valve....

That is a HUGE gain!!! The 7.5 spring is doing what the 11.5 spring did on valve 1, and the 11.5 spring is doing what my 16 lb spring did on valve 1...just nuts!

650/700 fps to 800 fps on the same spring....

This thread isn't about gaining fps per say but gaining fps with less hammer energy required!


I now need a spring in between 7.5 lb and 11.5 lb to tune! Or an even LIGHTER hammer!

[ackuric]

.34" poppet (stock) @ 2k psi has around 189 lbs of force when the valve is closed pressing on it with a light weight valve spring.

.25" poppet (modified) @ 2k psi has around 106 lbs of force when the valve is closed with a light weight spring behind it.

Above #'s @ 2500 psi (avg unregulated) is 234 lbs and 129.62 lbs.

I can't believe I am almost hitting 50 fpe on a 7.5 lb spring and 42 gram hammer...albeit the 800 fps was hit with no gap and would be inefficient for a tune, it's pretty wild when you recall all the complaints in the past about hammer springs being too heavy to make decent power with the SSG....all they needed was to slim down the poppet, and I went to the extreme of .25" just because, which is absolutely unnecessary and I'd say .29-.3" would be plenty of reduction on a poppet in a .25 cal marauder to allow much lighter springs...although YMMV with any other consequences of said modification.

[ackuric]

Pic of poppet/valve(ugly dremel scratch)/custom spring/custom end cap. Custom spring was NOT used in these tests. Just a look at what my hand-made poppet looks like. Custom spring rate you ask? 70 lbs! LOL. Custom end cap was made/used only because I forgot to order one from Crossman and didn't wanna have to swap those out every time I tested one valve to the other. It honestly probably is hurting my performance as it exposes a ton of the valves threads when installed opposed to the stock end cap. May just have to break down and order one on my next call to Crossman...or just remove the threads on valve 2 flush with the end cap




Pic of the tool one can use to either touch up the valve seat or reduce it, honestly I did neither on this mod but it was a great idea provided by Motorhead/Scott and I tweaked his idea a bit to conform to how I felt safe doing and valve seat work. I used a sand paper glued to a washer of .4" in diameter screwed onto a 1/8" shank put into the valve REVERSE and then hand spun / spun by a drill slowly. This mod would be GREAT for those staying under .1875" ports and really wanting a reduced poppet head for EASY opening of their valve.




Nothing special here, just a bolt with a bit of peek jb-welded into it, I used a phillips headed bolt so I had less material I had to drill out in order for it to work. I can't say its a huge improvement over a metal striker but it's certainly not worse..




Valve ported a bit further than I should have! I really shouldn't have but ah well...I'll test it (currently has 40 shots on it) If it holds up I'll inform the community on how I did it for about 10 cents and literally no serious tooling.

[ackuric]

If this mod does hold up, the max porting I calculated out to be around .23"..and could go full through with a tp made out @ .260" which would allow .015 walls which in my experience is plenty for a marauder in .177-.25 cal form. Max allowable margin of error would be down to .005 though on the valve/barrel ports! Probably a stretch so I personally wouldn't go much over .22" to allow slightly larger margins...I really can't disclose the method until I feel safe that IT itself is safe over time, and even then IDK, I am pushing it IMO...but with a .26-.27" poppet honestly this same method would SAFELY work so I may publish a how-to once I test this current poppet that is REALLY pushing it @ .25" with a .225" valve seat..

Yea .225 valve seal / throat

With .216 ports

That means the stem is...bah I am too embarrassed to say! .04 / 1mm in diameter!

[Motorhead]

Bye bye stem ... compression loading is IMO going to pretzel it in short order if not the snapping shut of the valve going the other way does not break it first.

JMO ...  as you were

[ackuric]

Bye bye stem ... compression loading is IMO going to pretzel it in short order if not the snapping shut of the valve going the other way does not break it first.

JMO ...  as you were

I agree Scott, that is why I do NOT recommend doing this as I am just testing and messing around. I found the results quite outstanding. I have taken the rifle apart to inspect and there is zero sign of defect/buckling on the stem so far, only 40 shots or so in though...

As I've stated though, a similar build with a .235" throat, .06" stem, and a .26-27" poppet would be MUCH more ideal and I actually intend on doing one similar in the long run if I stick with a big port of .216". A .06 stem is plenty and I have over 1000 shots on that stem with ZERO ill effects. If I go back to a smaller .19-.2 port I'll stick with a .25" poppet and a .225ish seat with a .06" poppet stem.

One must realize I am only reducing the stem to the factor closely relative to the pressure against it

The above .04 stem survived smacking the valve @ 2k psi with the 70 lb spring I shown pictured quite a few times so far as well...still I DO NOT recommend it as I am being a guinea pig on this and I actually am kinda TRYING to get it to fail to see how safe the .06" poppet is (50% more strength). Nothing like real world data!

[Motorhead]

If you did a hybrid type stem using say .040 to.063" tempered spring steel that went into the PEEK poppet head, but also bonded into the more typical 1/8" stem threw the body it likely would survive without fatigue.
* In other words the reduced diameter is precision ground and flexible spring steel where the reduced diameter within throat is at, full diameter threw body to hammer struck end.

Just thinkin out loud

[ackuric]

If you did a hybrid type stem using say .040 to.063" tempered spring steel that went into the PEEK poppet head, but also bonded into the more typical 1/8" stem threw the body it likely would survive without fatigue.
* In other words the reduced diameter is precision ground and flexible spring steel where the reduced diameter within throat is at, full diameter threw body to hammer struck end.

Just thinkin out loud

Great input. I don't think I'll stay so small on the hand ground stem but found the results interesting.  My efficiency  went back to normal after reducing spring on hammer..

[ackuric]

I only ordered peek+delrin @ .25" and really don't think I can make a poppet that small work with what I am trying to accomplish. It would work GREAT for .22 cal but I think I am going to revisit this with a poppet @ .295" which is a split between stock and .25"...the 40 shots the .04 stem survived was great but I have a feeling it is a huge ticking time bomb as I could flex that part of the stem by hand...the .06" stem I cannot do this to. I like to take risks in life but there comes a point where the line is TOO fine, no pun intended!

I need to find some peek/delrin at 5/16" to attempt a different poppet material! Reduced to .295", a properly turned peek/delrin poppet should seal GREAT on a .24-.265" seat that the marauder provides.

.295" poppet with .24" throat and a .09" stem would have good enough flow for a .21" exit port which SHOULD theoretically perform well at lower psi.

Not enough time in the day to do all the things I need to do! I am sure all can relate, lol.

On another note, peek may be VERY easy to machine/work with but getting a seal to hold over the long term is another story! I certainly made a mistake when doing some valve work I didn't clean the seat and when I installed the poppet back in, I created a few imperfections on the seat with brass remnants being squeezed between the poppet and the brass seat, and of course guess which material gave first?

Lack of attention to detail on my part!

[ackuric]

Another thought on this subject matter.

I reduced the poppet from .324" to .25" which is 22.8%

The above changed required me to go from a 16 lb spring to a 11.5 lb spring which is... 28.1%

I attribute the extra ~6% to the material being changed from whatever stock is to peek, and the seat reduced from .25~ to .235~

[ackuric]

Took valve # 2 apart, inspected, and the poppet actually wasn't what was leaking...was the GLUE! I couldn't even get that thing to seal with a stock poppet...the above dmg I mentioned in the prior post that the seat sustained was not sufficient enough across the entire seat area to cause a leak, at least imo.

I moved the seat forward .04" with a brass washer, it held up actually great, ZERO sign of failure, but due to me going with such large ports, a good portion of the original seat (where the exit port is) was destroyed which didn't allow full coverage/contact with the new seat to the old + glue. I actually believe the damage occurred when I dremeled around that area to smooth from the new seat to the exit port

I'll likely revisit the .25" poppet attempt with a fresh valve and much smaller ports as I don't think the two mix well without doing things like Scott suggested above to guarantee no poppet stem fatigue over time.

It'll be next week likely as I'll order another valve tmrw...but I'll attempt this again. Valve #2 will now become, oh idk...a paper weight! I actually may try to glue another washer/plug down but with how the old seat got broken I have little faith in obtaining a seal.

I did fire one off at 1400 psi for giggles with the leaky valve and made 46 FPE / 902 FPS with a JSB 25.4. That's some good power down low ayy!

[DougGuy]

I would suggest using a Cothran valve if you can get one.  I did all the tricks with PEEK poppets, yes they work but the numbers will always be severely restricted by the fact that the seat is so close to the exhaust on the stock valves that you are limited in what can be done with the stock valve.  In the long run, it's just simply not worth the time to tweak one and stay within the limitations.  I probably went through 4 stock valves modding them and porting, even moved the seat forward in one using stainless tubing set in JB weld.  It worked, but nowhere nearly as good as the Cothran.

By the time I quit wasting efforts on the stock valve, I had spent over $100 on them, and had enough time invested in my efforts to buy ten Cothran valves if I paid myself $5/hr.

[ackuric]

I would suggest using a Cothran valve if you can get one.  I did all the tricks with PEEK poppets, yes they work but the numbers will always be severely restricted by the fact that the seat is so close to the exhaust on the stock valves that you are limited in what can be done with the stock valve.  In the long run, it's just simply not worth the time to tweak one and stay within the limitations.  I probably went through 4 stock valves modding them and porting, even moved the seat forward in one using stainless tubing set in JB weld.  It worked, but nowhere nearly as good as the Cothran.

By the time I quit wasting efforts on the stock valve, I had spent over $100 on them, and had enough time invested in my efforts to buy ten Cothran valves if I paid myself $5/hr.

I have 22$ in the valve and 20$ in the poppet materials and about 2-3 hrs labor into the both, which even at 10$ an hour is only about 70 bucks where the Cothran is around 180$...and sadly hobbies are just that, hobbies not a source of income so I can't pay myself to play. So it's just a 22$ loss wrecking the above valve, and another 22$ for another attempt!

Even if I spend 150$ at the end of the day to achieve what I personally want (50 fpe with a 7.5-11 lb spring?) then I'll still end up saving money and having that sense of pride that I did it.

I don't disagree that the Cothran valve is a great valve but its MUCH better suited for very high power rifles...I am more-so learning and enjoying myself while doing some tinkering and attempting to do by hand what the pro's do with major tooling. No disrespect to them and not taking any credit away as what they do is quite amazing!

I certainly am not lacking performance, I have achieved both my desired power and shot counts and am just trying to make the valve easier to open. My next attempt should fair well as I will be very conservative on the ports (.18"-.19")

This was a proof of concept to me, and to only pay 22$ out of pocket to prove to myself something works is worth it to me!

[ackuric]

So I have given up on going as small as .25" on a poppet (maybe) for now, may revisit it someday..

I currently have a .295" stock poppet in my Valve #1 that I am testing and ordered some delrin @ 5/16 (.3125) that I'll likely reduce down a bit to test out, but I don't feel I can reduce peek down to where I want it to and keep it true/round without a lathe and I cannot find any 5/16 peek rod! I'll look again someday or maybe Scott has an idea where to get some?

The .25" poppet will have to be left to those with .177's and .22's.

I can't speak for what fps gains I have currently achieved going from .324" to .295" but they are certainly there.

7.5lb spring @ 1/4" pre-load with .324" poppet with 42 gr hammer prior to tear down was doing 500 fps on 25.4's = 14 fpe (was doing 45 fpe on this with a .25 poppet! max preload)

7.5 lb spring same pre-load with .295" poppet with a 35 gr hammer yielded 515~ fps with 25.4's = 15 fpe. Considering the huge drop in hammer weight, nearly 20%...I'd say the little modification / tweak was worth it to be able to sling a lighter hammer around and make more power without requiring more spring energy!

the 11.5lb spring makes 52 FPE now no problem as well with the .295" poppet and 35 gr hammer, where before it topped out around 48-49 fpe. I had to use a 13 lb spring to hit over 50 fpe on the .324" poppet and 42 gr hammer.

Can't say going to delrin will make a huge difference but I'll report back if/when I make one. I can see trying for a .275-.285" delrin poppet with the stock seat, leaving around .025" on sealing the surface, but considering I'd be doing it by hand I'd want bigger margins of error so I'd stick around .295" as I am now.

[Motorhead]

My last 36" piece of 5/16" O.D. natural PEEK came out of Interstate plastics here in Sacramento

[triggertreat]

I wonder how a coned shaped plug poppet would do instead of the traditional flat stopper style configuration when making one with a larger OD.

[ackuric]

My last 36" piece of 5/16" O.D. natural PEEK came out of Interstate plastics here in Sacramento

Thanks Scott!

[ackuric]

I wonder how a coned shaped plug poppet would do instead of the traditional flat stopper style configuration when making one with a larger OD.

You mean Tapered like this?  /   \

I believe most of the experts suggest/recommend a concave seat as that will allow less surface area to to create the seal? At least that is my interpretation of that.

My .25 peek poppet DID have a VERY concave seat/sealing surface and it sealed wonderfully. Just a shame I took the port so far on that valve and trashed it!

[triggertreat]

More like this /\, but ok. Just thinking out loud.