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PostPosted: Mon Mar 13, 2017 8:20 pm 
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Hi, just wondering if there is any benefit to making the inlet hole on the 13xx valves bigger? For example would it make pumping easier? I noticed someone on a forum talking about planning to do this but there wasn't an explanation of any proven advantage.
Thanks for any input!

Wes

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PostPosted: Mon Mar 13, 2017 10:25 pm 
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No advantage, and there is a disadvantage.... You will be increasing the "headspace", or wasted volume, and hence lowering the compression ratio.... Its only a big deal at high pump numbers, but it will lose performance there....

Bob

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PostPosted: Mon Mar 13, 2017 10:28 pm 
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Ok thanks very much! I was doubtful that it would help.

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PostPosted: Sat Mar 25, 2017 9:33 pm 
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I call it dead air space but the end result is the same, you've increased the volume of space than the plunger cannot compress. So yes the more dead space means pumping would be easier. Each individual pump would be easier but you'd need to pump more times to compensate. The oem setup already has this dead air space problem to a degree so you're making an already inefficient setup even worse. The hole is plenty big enough for the air to pass thru so you could reduce it's size to increase the pressure and volume of air delivered, but I doubt you'd notice the small gain.
The real fix imo is to get a flat top piston and sand the valve face down flat to match. By sanding it down you've made that hole shorter and thus reduced dead space, but the real gain is the flat top plunger is a way better setup. Or I should say it's what one would expect and the oem setup sux. If you look at how the valve face and plunger mate together you'll see one problem, lots of dead space. The other is the plunger and seal compress under higher pressure so it makes more dead space.
The problem with the flat top setup in the US is a win win, but since it bumps power it might make a Canadian a felon? You'd have to check your fps/power but the flat pistons are adjustable so you can dial it in to stay barely legal. Now where have I heard "Barely Legal" before....


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PostPosted: Sun Mar 26, 2017 1:44 am 
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Lol! Thanks for the explanation, I have a flat top brass piston on order, and have flattened and polished a valve ready for it, looking forward to trying it out. I'll have to readjust my hammer spring to keep it "barely legal", but looking forward to more efficient pumping!

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PostPosted: Sun Mar 26, 2017 3:27 pm 
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If you control power via the spring then you'll no doubt have a gun that holds air, so the valve will hold xx pressure after the shot meaning the first pump will be even harder but even less pumps needed to hit peak power.
I don't know how CA measures those guns, like does legal mean 10 pumps = <500 but if 11 breaks it is that ok? If so then I'd imagine to be legal you'd need to make it stay <500 when pumping 10x even tho the valve already has some pressure remaining? That would be unfair imo but "if" one were to completely obey the law I wonder how all that works?
Or would it be legal if you engraved on the side "Six Pumps Max!", or whatever pumps kept it legal?
So I guess between pumps and adjusting to the spring match it'll take some time to dial it in. Also, the flat top piston and the guns linkage etc will have some give under pressure so just setting the piston to kiss the valve at 0 pressure isn't enough, you need to make the piston a bit longer so it can still kiss the valve at full pressure. How much extra length you need I can't say, but tiral and error via pumping and checking velocity will tell you what the min length is. If it doesn't kiss at full pressure you lose out via dead space. Pita but fyi. As a result the first pumps you'll feel the piston bottoming out before the pump handle is closed. I'd imagine between that and the overall higher compression you should lube the pivot pins more often and with better grease.


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PostPosted: Sun Mar 26, 2017 3:44 pm 
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Thanks I never thought of that, about needing to leave it a little bit long to keep it tight under pressure. More stress on things as you say, will have to keep an eye on those pins. What would you recommend for a good quality lube? I've mostly been using pellgunoil on things. I do have silicon grease as well as the Crosman silicon chamber oil.
Here is my setup. I've got a fitting through the side of the tube and valve and auxiliary tank on it to make it a pcp pumper. That's why I put a lighter hammer spring in and adjuster on the back to keep it legal. Once I have the flat top and have it adjusted I plan to put a stock unmodified end cap on with a hammer spring preadjusted to the right power, so I won't be in trouble with legality by someone turning in my adjuster and making it shoot too fast. ImageImage
The big tank gives 50 shots from 1100 to 500psi and the little 12g quick change adapter with cartridge gives 10 shots in the same range of psi and fps (500-450).

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Last edited by wesb2007 on Sun Mar 26, 2017 4:00 pm, edited 2 times in total.

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PostPosted: Sun Mar 26, 2017 3:46 pm 
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I apologize for them being upside down lol. (fixed them now)

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PostPosted: Sun Mar 26, 2017 6:08 pm 
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That looks pretty cool. Gauge is very close to standard disco.

What pressure do you use at fill stop?

-D.S.

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PostPosted: Sun Mar 26, 2017 7:47 pm 
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Thanks, the way I have my hammer spring set I don't fill it past 1100psi, that way I get fifty pretty consistent fps shots. If I fill it higher then the spring tension isn't strong enough without adjusting. It'll shoot very consistently down to 500psi. Sorry, that's with the big tank and 9-10 shots with the little 12g. Here is what I used to connect it, bought off AliExpress. Image

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PostPosted: Sun Mar 26, 2017 10:13 pm 
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I got enuff projects already....

It's darn tempting, but I better finish (loooong list) what's on my plate first :wink:

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PostPosted: Sun Mar 26, 2017 10:39 pm 
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Right! I'm really tempted to try that 2100 pumper project combined with my pcp add on, would be sure a lot quicker to fill that tank with your gun! Someday one of us will try it out maybe, see who gets there first [SMILING FACE WITH SMILING EYES]!

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PostPosted: Sat Apr 01, 2017 6:11 pm 
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I don't think the additional force on the pivot points is a big deal, but it is something to consider. So imo just use better lube and and/or lube more often.
I use good bearing grease and tungsten disulfide. The tungsten is a powder like moly, but I hear tungsten is hard to get/expensive in CA? I'm in the US so it's like $10/oz, and an oz goes a loooong way, maybe a lifetime supply for most peep. You mix it with grease or oil in whatever % you like to make a super lube. The big bennie is imo is you get it in dry powder so you can apply that directly to the parts, metal, plastic, wood etc and impregnate the material with it, then apply the mix you make over that. You also also use just the tungsten, but it's almost useless against rust so not a good ideal for steel.
Option two is to buy moly powder instead (easier to get in CA?) which is perfectly fine, but tungsten is slightly better. Option three is buy premixed moly paste, which is more $, you miss out on the dry part and you're stuck with their formula (whatever that paste part is), but you can thin it with motor oil if needed. Most peep that buy special lube get moly paste, which is good stuff for most things but not as good or versatile as getting the powder and making custom mixes.
Most people just do what you're doing; oil it with pellgun oil, which seems to be fine for most people so any upgrade at all is a bonus.
Do not use silicone on the pivot points, silicone is not a lube for metal, it's for synthetic stuff like seals.
The internals of the valve are a mix of metal and synthetics but no metal under stress so silicone is fine, and some parts like the oem plunger do not like most real (petrol) lubes so you have to be careful. The plunger will shrink and harden, or dissolve. You can use silicone for the plunger/valve if you want, but I'd use the pelgun oil which is a real oil but apparently has little affect on the syn parts. That why when the pellgun oil migrates around it's not a big deal on parts that would not like silicone. I have no doubt that the plunger will live longer with silicone than pellgun oil, but up to you. If you go to a flat top deal then you'll be using O-rings which imo will last longer than the plunger when exposed to petrol, and of course replacements are easy to find, cheap, and don't make a mess. "If" the oem plunger breaks down you have to (should) take the valve apart and clean the goop out.
So long story short, I'd prep the areas that see stress with some sanding, strip them clean, dry lube them (tungsten or moly powder), grease them with the mix and you're good to go. After whatever time you feel is good you can add a drop of pellgun oil or motor oil to the pivot joints, and at some point I would take it apart and re-dry lube/grease. You can also mix the dry lube with pellgun or motor oil, which is imo especially useful for joints you can't or don't want to take apart. As mentioned it's probably not a big deal since they usually work fine with minimal maint, I just like to go the extra mile. If you're into guns or other mechanical toys, or just have to maintain mech stuff, then tungsten (or moly) powder is a great thing to have. Graphite and motor mica are some other dry lubes, each with it's own range of uses.
I like the gun in the pix. Did you adjust the parallax in that scope to work at airgun ranges?


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PostPosted: Sun Apr 02, 2017 5:16 am 
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Wesb2007

I see you have a foster fitting threaded into the large tank. How thick is that tank?
I sure would not want it to blow out!!

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PostPosted: Sun Apr 02, 2017 5:24 am 
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Thanks for the tips! I'll have to check out prices on tungsten or moly paste.
I did turn the ring in the end of the scope out, so it's parallax free at around 25 yards or so, but still pretty bad parallax in my basement (only 25'). I don't think I better adjust it further cause it looks like it's getting close to the end of the threads. Definitely wishing I bought an ao scope, would have been a lot handier! This one was really cheap though, and nice and bright outside.

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