Do I really need a valve spring for a low pressure build?

[Euphie]

I was playing around a bit a bit earlier trying to get reliable cycling at low pressure, and it would seem to me that the only way I am getting good cycling between 180-250 psi with a New Designs low pressure valve is with the valve spring out of the marker. This valve already has about as much flow as looks possible to get, and I am using a huge volume of post regulated air sitting behind the valve with both a low pressure chamber an an expansion chamber (with no ball bearings in it, so it is just an air chamber under the valve now)

My worry is, that it won't be as consistent without the spring to close the cup seal, but without a chrono it seems hard to tell if this is the case. When I had a valve spring in, it didn't seem to matter which mainspring I used it would shoot in that pressure range but, rapid fire would result in double shots and failure to recock. I plan on using a Maxflow regulator so that is why I am targeting that range, but for testing I have just been setting my Air America Apocalypse that low, I don't know if it matters but still.

Also I am noticing that at super low pressures, I can shoot paint or turn the bolt upside down, but if I just dry fire I have trouble recocking, is this normal?

[Jonnydread]

The recocking issue is normal. Low pressure blowbacks often need backpressure to recock reliably.

I'm unsure about the valve spring. I would probably keep it in there as a just in case, but my gut feeling is that it would probably function without it.

[Shaftski]

spring is doing more than just closing the valve. it is also there to keep the cup seal/pin on the correct axis and make sure it doesn't dance around on the valve face, ensuring a proper seal. without offering too much resistance vs the main spring.

it may be sealing, but more than likely micro-leaking at the valve face. would not be noticeable unless you have a gauge mounted near the valve/LPC and let the marker sit for a while. an azodin KP3 can "work" at lower pressures than designed, but that cup seal interface will micro leak and cause shootdown and loss of tank capacity.

[Toestr]

I've heard of getting heavy kick on LP stbbs because the dwell is so high.

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[Seajay]

That's a pretty low attempt for that valve There isn't enough face to run without a valve spring, although you can get it to cycle like that. Part of the valve spring operation is to keep it aligned and to keep the force to open consistent.

I'm not sure if that valve the pin will fall out, or jam, if extended open too far when not pressurized.

What you can try is find a pen spring or soft spring from your hardware store. I've had some luck doing this when trying this same kind of setup.
I always seemed to end up at about 300 psi though once I chronoed for velocity.

There is almost zero "kick" on LP spyders. What sometimes happens is you need a very strong striker spring and a soft valve spring to hold the valve open long enough to reach velocity. That strong striker spring can make the shot feel hard. If the recock cycle seems angry you can try different springs to change the cycling behavior to be softer.

Don't forget your rear bumper.

[scottieb]

I've never had good luck leaving out the valve spring. I'd keep it in there.

Have you plugged the blowback hole in the body?

Recocking issues without a ball, or swab, or something in a LP Spyder is common.

[Euphie]

I've never had good luck leaving out the valve spring. I'd keep it in there.

Have you plugged the blowback hole in the body?

Recocking issues without a ball, or swab, or something in a LP Spyder is common.

by blowback hole, do you mean that pin that goes through the middle of the body?

I suppose after reading these I will hunt for a non paintball spring, I have so many Spyder springs but the valve springs all seem way too stiff, which tells me these kits really don’t have low pressure in mind, but I want to see just how soft I can make operation

[scottieb]

by blowback hole, do you mean that pin that goes through the middle of the body?

No. That is the valve pin. The blowback hole is a hole in the underside of the body. You'll find it about halfway between the slot for the sear and the hole for the valve screw, but closer to the hole for the valve screw.

[Tarsun2]

i think angel used a magnet in some of their models rather than a spring lol

the star washer "should" keep the pin in line. (kindda) ((may one on each end)) (((possibly)))

neo power valve possibly?

[Seajay]

by blowback hole, do you mean that pin that goes through the middle of the body?

I suppose after reading these I will hunt for a non paintball spring, I have so many Spyder springs but the valve springs all seem way too stiff, which tells me these kits really don’t have low pressure in mind, but I want to see just how soft I can make operation

It's not that they don't have "low" pressure in mind, anything under 800 psi is considered low pressure. Normal low pressure mods are ~600 psi, and really good LP setups are 300-400 psi.
Anything less than 300 psi is just pushing the edges of what you can do with a standard Spyder (not a VS, RX, or AMG body). Extreme low pressure setup if you will. It does take a certain combination of parts and springs to achieve this low of pressure, which is part of the fun. Also keep in mind no Spyder is the same and you have to experiment because sometimes what you think should work doesn't, and the reverse works perfectly.

[Tarsun2]

im sticking by the neo power valve. its cheap and allows you to adjust the spring pressure on the fly.
wait, does it only work for the non-compacts..?

[scottieb]

Yes. It only works in a full size body.

[Seajay]

For all my time with Spyders I've never tried the Neo Power Valve. I really should get one lol.

[Euphie]

I actually hadn’t heard of one till now, looking at photos looks like the Azodin Zero system, I have 5 Spyder bodies and a bunch of parts of these things can still be purchased I might have to try one too

[Euphie]

So I did make it to a chrono over the weekend and it was surprisingly reliable with sealing even at very low pressures, but seemly random decocking kept happening, often in the 200-300psi range and occasionally in the 300+ PSI range. It just feels like the valve isn’t opening long enough I put so much post regulated air in front and of the valve that I can shoot 8-10 shots once I turn my tank off, so it just isn’t consuming enough air on each shot, but if I hit the valve harder then I will have more kick going on

i have the feeling this will be a complex balancing act, but I cycled through over a hopper and the valve never got stuck or anything even without a speing which surprises me, I will probably still end up running one based on the feedback here though

[Seajay]

So I did make it to a chrono over the weekend and it was surprisingly reliable with sealing even at very low pressures, but seemly random decocking kept happening, often in the 200-300psi range and occasionally in the 300+ PSI range. It just feels like the valve isn’t opening long enough I put so much post regulated air in front and of the valve that I can shoot 8-10 shots once I turn my tank off, so it just isn’t consuming enough air on each shot, but if I hit the valve harder then I will have more kick going on

i have the feeling this will be a complex balancing act, but I cycled through over a hopper and the valve never got stuck or anything even without a speing which surprises me, I will probably still end up running one based on the feedback here though

Decocking as in the striker isn't quite resetting? This is somewhat expected at this low pressure. There are number of things to try... different valve, cup face the striker (more air surface area), lighter striker, more spring combos, increase air volume, tighter ball to barrel match to improve back pressure, reduce wasted air at the bolt (blowby).... all of the above.

You are at the limit of that Spyder's stock capability without modification.

[Myrkul]

I like to set up my spyders for the weakest springs possible, and I've noticed that stock VASA's (on the compact body style) typically reduce the flow too much to get away with crazy light springs. I've drilled several out and they work MUCH better. The other thing you can do is modify a Timmy front block and use that, they have much better air flow.