New 392 clone build

[Tack Driver 10]

Used a highly modified 392 valve on this build.
7" stroke and .750" diameter Disco tube.
Got the following with 14.3 CPHPs and a 24" barrel

05 pumps=625 FPS
10 pumps=826 FPS
12 pumps=891 FPS
15 pumps=960 FPS
20 pumps=1034 FPS

With a 7.25" stroke x .775" diameter tube, 800+ FPS on 8 pumps should be a cake walk with a 392.

[Psipumper]

Sorry for leaving you hanging. Rolling again. I was not able to get the delrin exhaust valve to seal. Tried remaking with white delrin but still sealing issues. I decided to skip the delrin for now. Average results are:
Undercut stock exhaust valve stem =742 fps.
Angled transfer hole with Dremel tool = 767.
Changed transfer hole to a D shape = 765.
New improved hammer = 771.
Reduced valve volume with plastic spring spacer=782 fps.

Final of 782 . I think the delrin is possible but the valve guide hole is too sloppy of a fit. I am going to sleeve the stem hole and build a smaller .093” stem delrin valve then retry 800 fps in the future.

[Habanero69er]

Impressive numbers.

[Psipumper]

No comments? How about this photo.  Double lifetime guarantee.

[Rob M]

WOW, that front assembly is bad-ss .. that could be a commercial product tomorrow and sell like crazy

[2K1TJ]

Beefy! I like!!

[Rob112o]

Sign me up for one. That's awesome

[CraigH]

Super heavy duty assembly - makes my bit of 1322 two-screw reinforcement look rather puny!   

[Psipumper]

WOW, that front assembly is bad-ss .. that could be a commercial product tomorrow and sell like crazy

I had some reservations for that reason.  We know where we saw it first gentlemen. I would sell the rights to  market . I will send you the blueprints to make them for your personal use.

[Psipumper]

I found some more potential power. Valve diameter was .750 in front of o-ring. The rest of the valve is .767. Soldered it up to turn down to .775.

[2K1TJ]

Every little bit helps...

What kind of solder is that? Think it's up to handling the stress?

I've never thought to measure that part of the valve. I have thought of putting a back-up ring above the o-ring both on the valve and piston to reduce headspace. As I understand it, these are used to help prevent your o-rings from extruding. I think they would have to be on the opposite side of the o-ring that I am referring to to serve that purpose, again, if I understand correctly.

And since you're going all-out, you might consider putting a small pin/rod on the front end of the check valve to fill the space between the check and the tip of the cone.

[Psipumper]

The solder is 60/40 rosin core. I didn’t do a very neat job but if it sticks good enough to survive the lathe machining , it will hold up in the gun.  I think those backup rings require the groove to be machined wider to add them.  Appreciate the advice on the air inlet hole space.

[2K1TJ]

The solder is 60/40 rosin core. I didn’t do a very neat job but if it sticks good enough to survive the lathe machining , it will hold up in the gun.  I think those backup rings require the groove to be machined wider to add them.  Appreciate the advice on the air inlet hole space.

Good point on the solder. Let us know what you gain from that.

[Psipumper]

The new bar is 825. I checked today and the results were impressive. Kinda cold outside but  the gun was kept and pumped indoor. 5 shots = 797,796,797,801,797. I decided to take a few shots  with fewer pumps.  3 pumps was 552. 4 pumps was 625. 6 pumps  726. I tried a JSB 18.13 at 8 pumps for 730.
I am beginning to like this clone. This PA platform is a blast.

[kelvinator]

I like the idea of getting the most out of the least, especially on a pumper.
Whenever I mod a valve I usually stuff it a little instead of increasing the capacity.

[2K1TJ]

The new bar is 825. I checked today and the results were impressive. Kinda cold outside but  the gun was kept and pumped indoor. 5 shots = 797,796,797,801,797. I decided to take a few shots  with fewer pumps.  3 pumps was 552. 4 pumps was 625. 6 pumps  726. I tried a JSB 18.13 at 8 pumps for 730.
I am beginning to like this clone. This PA platform is a blast.

Nice numbers. What do you have planned next?

[Psipumper]

I like the idea of getting the most out of the least, especially on a pumper.
Whenever I mod a valve I usually stuff it a little instead of increasing the capacity.

Yes, high efficiency  is what is significant about this gun. Makes the “air conserving pumper” concept obsolete.  625@4 easy pumps every time. No guesswork.

[Psipumper]

Just wondering as I move along if I am providing enough explanation or not. I have some good stuff coming to address one of the biggest design flaws of the PA. Many of the mods are already on the internet and I didn’t won’t to repost the details of them unless someone asks a question. Some  of my mods are a first ,at least for “as seen on the internet”. I feel guilty for providing stuff that my be hard to obtain for the do it your self person.

[2K1TJ]

Just wondering as I move along if I am providing enough explanation or not. I have some good stuff coming to address one of the biggest design flaws of the PA. Many of the mods are already on the internet and I didn’t won’t to repost the details of them unless someone asks a question. Some of it is a first at least for the internet.

I think you're doing a fine job. I am guilty of not doing this myself sometimes, but try to remember to take pics as you go. Especially when doing unique mods.

Can't wait to see the "good stuff" you have coming.

[Tack Driver 10]

Just wondering as I move along if I am providing enough explanation or not. I have some good stuff coming to address one of the biggest design flaws of the PA. Many of the mods are already on the internet and I didn’t won’t to repost the details of them unless someone asks a question. Some of it is a first at least for the internet. I feel guilty for providing stuff that my be hard to obtain for the do it your self person.

Any plans to flat top the valve/piston?

Fairly easy and will yield good gain.