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I have never built a valve before, but I thought that I read the valve seat works better if it is not tapered. I may be wrong, its been a long time since I was reading on it.
Ok with tophat at .080″ it shot
150 gr. 827 fps 227 fpe
126 gr. 886 fps 220 fre
118 gr. 944 fps 233 fpe
Don’t know why the 118 gr shot the hardest.
I raised the tophat to .095 and tank dump came back. It is set at .089″ now but I need to work on completing the gun. I cut the nylon out of the barrel guided hammer and have to redo it. Wasn’t happy how it was riding on barrel. This hammer had glue issues and I think that was the problem. Going to century spring to get some more springs today also.
Thanks Pab. I think that was the problem. I did put a o ring in the stem and hardware store had a little stiff spring. Tophat is now .80 and it shot 150 gr at 784 fps. I will make it .100″ and see what happens. Thanks for the input guys
Someone along the line said they had to change the breech volume to eleviate tank dump.
Thanks. Looks like tophat gap is close to .140″. I will make a acetal spacer and bring it down to .100″. If that doesn’t work I will try .090″.
The micro- meter spring is very stout, you could maybe make a disc with an air hole to reduce , or like the micro tank a sleeve that goes around the spring.
First thought was maybe the stem oring expanding and gripping the stem open, but I see you dont have that oring yet…
You sure the breech is travelling nice and free? Those orings in there expand a fair bit when under pressure… Enough to grip the barrel long enough, keep the valve open and initiate a dump…??
Or the stem stroke is too long, aloowing time for the pressure to balance enough to dump??
Caution! – Putting a .177 barrel on a condor valve without changing out the valve spring will cause blow back and tank dump!
caught on quick, did ya?
doug,
you should try my idea of using a stack of the proper belleville springs around the stem to assist in return. otherwise the back pressure is gonna get self defeating at these power levels.
There are only a few things that can cause a tank dump. The Pressure out side the tank is greater than or equal to the pressure inside the tank, such as a stuck pellet or the barrel being to small. This is most common and if your valve is putting out that much air, could be your problem.
Another cause is that the valve and seat are not aligning on closure, spring being to strong and pushing off to one side, tophat or stem getting stuck in the bolt or valve guide. With no spring pressure at all the stem should travel freely but must be held in alignment the full travel.
I use a very light spring in my valve, it barely holds the tophat up with the tank empty.
I just looked at a pic of your new valve and in my opinion, and I mean my opinion only, the air travel is going around the valve and holding it open. There is no pressure against the bottom of the valve to close it . No spring is going to overcome 3000 psi to close the valve.
I could be wrong, have been before, good luck and I hope you get it to work, that setup is awesome.
I think the following warning should be a safety sticky if it isn’t already.
Caution! – Putting a .177 barrel on a condor valve without changing out the valve spring will cause blow back and tank dump!
It’s the valve in my valve build. Finished it and there is pics. What info do you need?
post a diagram of this valve and i could likely tell ya…
3000 psi blow gun. I put a stock condor spring over mine spring and it still did it. Going to get some stiffer springs tomorrow.
try a stiffer return spring to close that valve up faster.
is the hole tank dumping?
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taco bell?
😆