13xx Max Smoke Pro Valve

[Rob M]

very nice work Ron.. very high pressures achieved.. Had a thought, which i might actually try one day.. Ever think about taking a 17mm reamer ( .669) and running it down the tube till it hits the valve face ? this would free up quite a bit of swept volume and decrease the pump strokes ..youd need to make a new front pivot cap and new piston , but the gain would be 16% per stroke. probably be easier to just start with a larger tube (-;

[rsterne]

Not to sure I would do that.... Even assuming the reamer didn't catch on the pumping slot and go off center, the wall thickness would be reduced from 0.065" to 0.040".... If the steel is 1018 DOM tubing (a common type for such use), at 2500 psi the safety margin would only be 2.3 to yield and 2.7 to burst....

Bob

[Tack Driver 10]

very nice work Ron.. very high pressures achieved.. Had a thought, which i might actually try one day.. Ever think about taking a 17mm reamer ( .669) and running it down the tube till it hits the valve face ? this would free up quite a bit of swept volume and decrease the pump strokes ..youd need to make a new front pivot cap and new piston , but the gain would be 16% per stroke. probably be easier to just start with a larger tube (-;

I wouldn't feel comfortable removing much material from the stock tube as Bob stated.
A 3/4" ID tube would be a better alternative like an MK tube.
I'd like to try polishing the inside of the tube though.
I'm curious how much the stamping on the tube affects power.
The stamping is right at the high pressure end of the stroke, might try a 760 tube which is smooth (like me...LOL).

Both  of the Pro valves had trouble sealing the first few pumps.
Rapid pumping minimized the loss but it's time to get it right.
I used what I had on hand, a pen spring for the valve stem and it only provides 10 oz of force.
Need about 3+ lbs to make a good seal so ordered some springs from Grainger.
The stock valve provides 8 1/2 lbs of pressure on the stem for reference.

Found some springs at Ace but the ID is .150" so bushed it with some brass.
The wire size is .032" so also a little heavy but provides 3 lbs of force.
The new springs have an ID of .130" with a .029" wire size which should be ideal.
I'll wait for the springs to arrive Wednesday and choose the best alternative.

[Long_Gun_Dallas]

I was wondering about that, haha.  The seals actually shutting initially, I mean.  I was wondering how consistent your velocity was for any given number of pumps.  Almost certainly wouldn't be if it wasn't sealing as you stated. 

Looks great.

[Tack Driver 10]

Got the new springs and fitted one on the Min Max Smoke Pro valve.
Fit nice and provided 3 lbs of force.
Also took a "79" pump tube from a 760 and prepped it for the 13xx.
The BackPacker tube had some pits in it so wanted to try a different tube.
Even though the 760 tube is 40 years old (and rusty) the bore looked good so went with it.
Sanded off the rust from the outside front of the tube.

Put everything together and ran some pressure tests.
Was getting 2900 PSI with 15 pumps and 2100 with 10 pumps.
Before I was getting 2600 and 1950 so I knew something was amiss.
Long story short, was I over lubed the gun reducing the volume even more.
Pressure went up but velocity was down with the 24" 17 cal barrel.
Tried blowing off the extra lube with a little alcohol which helped but will need to clean out the valve.
The gun did dump almost all the air at 2900 PSI except for a slight puff.

Before taking the gun apart........
Put a 10" 22 cal barrel on the gun and gave it 10 pumps x 3 with 14.3 CPHPs.
Got 568.2, 567.8, and 572 after adding a little oil.
That's 10.25 FPE with 10 pumps and about 1900 PSI.
So 10-10-10 can be achieved with a 1322.

Tried a 17 cal 10" barrel and got 650 FPS 7.41 FPE with 7.9 CPHPs with 10 pumps.

Put a 14.5" 22 cal barrel on and.....
10 pumps 593 FPS 11.16 FPE
12 pumps 631 FPS 12.64 FPE
15 pumps 698 FPS 15 .47 FPE
Somewhat better than the Max Smoke Pro Valve

[Tack Driver 10]

But wait, there's more!
I have yet to unleash my secret weapon.
Stay tuned, until then.......

[Rob M]

the 10-10-10 is very impressive.. nice work

[Tom Tucker]

Agree, 10-10-10 is a serious benchmark.  This is a great thread!

I wonder if you could maintain that with more valve volume and less pressure - those pressures sound sooo high.  My thinking is that you would...

I suspect that most important advantage your setup has over the typical flat-top piston/valve with o-rings is the near-zero headspace you have achieved.

But before you change the valve again - I'm curious about what kind of performance it gets at 3-5 pumps.  Something tells me that it does really, really, well there.

For reference, my gun that does 9-10-10 with just slightly more volume than stock gets 3.4 FPE at 3 pumps, 4.4 FPE at 4 pumps, and 5.5 FPE at 5 pumps.

[Tack Driver 10]

Agree, 10-10-10 is a serious benchmark.  This is a great thread!

I wonder if you could maintain that with more valve volume and less pressure - those pressures sound sooo high.  My thinking is that you would...

I suspect that most important advantage your setup has over the typical flat-top piston/valve with o-rings is the near-zero headspace you have achieved.

But before you change the valve again - I'm curious about what kind of performance it gets at 3-5 pumps.  Something tells me that it does really, really, well there.

For reference, my gun that does 9-10-10 with just slightly more volume than stock gets 3.4 FPE at 3 pumps, 4.4 FPE at 4 pumps, and 5.5 FPE at 5 pumps.

Too late, the singing fish is in the can....LOL
I took the gun apart this morning, combining the back half from the Min Max Smoke Pro valve and the Billy Bass front end. 
I don't think there will be much difference but I have to give it a try.
Our hero Billy Bass was very insistent.

Like underwear, one size does not fit all....LOL
The idea is to produce a valve that will perform well with a short barrel but have the ability to scale up to a longer barrel.
For a short barrel, small volume and high pressure, a long barrel will do best with more volume and lower pressure.
Tuning is achieved by varying the valve spacer.

When I test the gun I'll also try 3-5 pumps to see how it does.

[Long_Gun_Dallas]

Seriously impressive numbers.

Do you mind me asking what type of lube you use?

My 1322 maxes out at ~15fpe (14.5") at twice the pumps.  550fps @15 pumps, 16gr.  But Im still struggling with piston seal failures.  No oring I've tried yet is durable enough.  Or maybe my tube to piston clearance is too high.  Either way, I don't have tooling to remedy. 

[rsterne]

550 fps with 16 gr. is less than 11 FPE....

Bob

[Tack Driver 10]

Seriously impressive numbers.

Do you mind me asking what type of lube you use?

My 1322 maxes out at ~15fpe (14.5") at twice the pumps.  550fps @15 pumps, 16gr.  But Im still struggling with piston seal failures.  No oring I've tried yet is durable enough.  Or maybe my tube to piston clearance is too high.  Either way, I don't have tooling to remedy.

I use silicone shock oil on the piston seal and 50wt racing oil on the pivots.
Silicone is more viscosity stable and is available in a wide range of heavy weights.

https://www.ebay.com/itm/Team-Losi-Racing-74021-Silicone-Shock-Oil-Six-Pack-50-60-70-80-90-100wt/202668415433?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649

If you're having seal problems try 90 duro polyurethane seals.
They're super tough and abrasion resistant.

https://www.theoringstore.com/store/index.php?main_page=product_info&cPath=367_459_460&products_id=16241

[Long_Gun_Dallas]

550 fps with 16 gr. is less than 11 FPE....

Bob

He's only testing his to 15 pumps.  Mine will do 650fps at 30.  Still lousy results in my opinion, but I don't have the means to do any better.

Thanks for the advice

[Tack Driver 10]

I have sad news as it seems Billy suffered a hernia.....LOL
The Teflon check valve extruded out the front of the valve during testing.
I was able to get one 10 pump chrony test.
I then pumped to 15 pumps and the pump arm couldn't be pumped past 3/4 stroke.
This version doesn't have a gauge so don't know what pressure it made.
Once the gun is back in action I'll limit the pumps to 12 and see how it does.

14.3 CPHPs and 14 1/2" barrel
10 pumps 602 FPS 11.51 FPE vs (593 FPS 11.16 FPE previously)

I took the gun apart and prepped the big fish for emergency surgery.
Made a new check valve from virgin white Delrin.
How's the patient doing?

[rsterne]

It is the large diameter of the check valve that is the problem.... When making Delrin poppets for PCPs, if you go too large in diameter for a given pressure, the Delrin will extrude into the valve throat.... Disco poppet on left, PEEK replacement on right.... bearing on the same valve seat....



Here is a photo I have of an MRod poppet (black Delrin I believe) that was used in a 0.281" valve throat…. They will work flawlessly in a 1/4" throat at 3000 psi.... will start to distort slightly but survive OK in a 0.266" throat.... and extrude to the point of sticking in the throat and require a ridiculous amount of additional hammer strike in a 0.281" diameter throat (ie unsuitable in that diameter)….



Bob

[Tack Driver 10]

It is the large diameter of the check valve that is the problem.... When making Delrin poppets for PCPs, if you go too large in diameter for a given pressure, the Delrin will extrude into the valve throat.... Disco poppet on left, PEEK replacement on right.... bearing on the same valve seat....


Here is a photo I have of an MRod poppet (black Delrin I believe) that was used in a 0.281" valve throat…. They will work flawlessly in a 1/4" throat at 3000 psi.... will start to distort slightly but survive OK in a 0.266" throat.... and extrude to the point of sticking in the throat and require a ridiculous amount of additional hammer strike in a 0.281" diameter throat (ie unsuitable in that diameter)….

Bob

Bob, Thanks for the info.
I had a similar incident happen when I was making the balanced valve as you may recall.
The Teflon stem stretched and failed when high pressure was applied.

The opening to the check valve is .242" so Delrin should hold, hopefully it won't blow the front end off....LOL

[rsterne]

Pulling the poppet apart at the bottom of the O-ring groove is a different problem.... In that case you are dealing primarily with the tensile strength of the plastic used.... In the case of extruding through a hole, you are dealing with the compressive strength, and also with a factor called "creep", which is the material flowing like a very thick liquid when exposed to pressure over time....

Bob

[Tack Driver 10]

I had to take a brief respite, I guess you could say, "I was gone fishing".....LOL
Took the Min/Max Pro valve and increased the volume by a guesstimated 50%.
This lowered the pressure quite a bit so ran some tests.

10" 22 cal barrel, 14.3 CPHPs
10 pumps 513 FPS 08.35 FPE 1500 PSI (vs 2000)
15 pumps 614 FPS 11.97 FPE 2150 PSI (vs 2900)

14.5" 22 cal barrel, 14.3 CPHPs
10 pumps 583 FPS 10.79 FPE 1500 PSI (vs 2000)
15 pumps 683 FPS 14.81 FPE 2150 PSI (vs 2900)
18 pumps 725 FPS 16.69 FPE 2500 PSI (not tested)

The lower pressure made a big difference with the 10" barrel.
FPS dropped about 55 FPS with 10 pumps, not tested previously with 15 pumps.

The 14.5" barrel only dropped about 10 FPS at 10 & 15 pumps and did well with 18 pumps.

The shorter 10" barrel likes small valve volume and high pressure.

Next up, Billy Bass , round 2.

[rsterne]

The shorter 10" barrel likes small valve volume and high pressure.

Not really surprising.... If you want some impressive numbers, pump the new larger valve up to the same pressure as before (2900 psi) with a long barrel....

Bob

[Tack Driver 10]

The shorter 10" barrel likes small valve volume and high pressure.

Not really surprising.... If you want some impressive numbers, pump the new larger valve up to the same pressure as before (2900 psi) with a long barrel....

Bob

OK yes, I do want impressive numbers (who doesn't?) so I  put a 22 cal 20" barrel on the gun.
It's the longest I have in 22 cal and previously got 760 FPS, 18.39 FPE with 18 pumps with the Max Smoke Pro valve.
It has a bigger throat, volume and ports than the Min Max valve but no gauge.

I think it'll take 22 pumps to make 2900 PSI and maybe 800+ FPS, 20 FPE?

Another thing I want to try is honing the pump tube.
This tube is 40 years old from a late 70s Pumpmaster 760.
Probably has some battle scars that could benefit from some TLC.
I have 600, 1200, 2400, 5000, and 7000 grit sandpaper to smooth things out.