vulcan .25 unstable velocity !!

Sorry to hear you need to go back in and work on the regulator, but I’m not surprised by this result. At least, you are now capable of getting into the air cylinder.

Even in the US, one cannot simply go to the store and buy a regulator tester. I can understand the challenge where you are would be greater.

You will need to completely disassemble the regulator and at the very least, clean the components, re-lube them with silicone grease, check that the seating surfaces are undamaged and clean, then reassemble.

I think actually replacing all internal and external o-rings is a reasonable extra step if you have access to those parts. I don’t know the sizes and specs of the rings for those inside the regulator.

By “adjust by angle,” he meant that adjusting the regulator by measuring its length is imprecise and inaccurate on the Vulcan regulator because the changes in length are very small. It is better to make a ink mark on the adjustment piece and also a mark on the regulator body. You can keep track of the angle between the marks as you turn the adjuster. A mere 2-3 degree shift will change the pressure about 10 bar. Changes are easier to track by angle than total length of the regulator.

This is going to be a much longer process than with a regulator tester, but doable with patience. You will need to shot multiple shoot strings and plot the velocity vs pressure curves. Takes a lot of time and pellets. You may be tempted to skip plotting the actual curves, but plotting out the curves is absolutely needed if you don’t have a tester.

I would begin by turning in the adjuster all the way in until you feel the resistance of it seating. Then back it out 90 degrees. That will probably be too low a pressure, but you want your first guess to be too low. That will let you shoot your first shot string while definitely regulated. The strategy is verify you are getting regulation. Then, incrementally adjust until the regulated pressure is the desired pressure.

Repeat taking apart, reassembling, adjust regulator, filling to 200, shooting a shot string down to 100 bar, plotting the fps vs pressure curve. Filling to 200 and shooting to 100 gets you data across the pressure range of interest.

Look at your plotted curve and find the pressure at which the velocities change from the level portion and begins to climb or drop. That is pressure your regulator is currently at. Whether it climbs or drops at the end of regulation depends on your hammer spring tension. Don’t worry about that for now. Just look for either change from flat on your plotted graph. Leave the hammer spring tension constant during the shot string.

If the regulator set pressure is not 140-150, take the whole thing apart again and adjust as needed. Loosen the jam nut, turn in 2-3 degrees to reduce pressure, out 2-3 degrees to increase pressure. Tighten the jam nut without changing the angle between adjuster and regulator body.

Once you have the initial regulation set, you can work on tuning the hammer spring tension for optimum velocity to match the regulator pressure. Basically, you set the HST to make the velocity just so the end of regulation drops instead of climbs. Alternatively, you set FPS and adjust regulator to modify the shape of the curve at end of regulation. They interact. Each regulator pressure has an associated ideal HST set point. Again, this is for later. Concentrate on getting regulation working.

If you can’t get regulation working, the regulator will need replacement.

Well, Hootie Hoo, that’s why you get the Big Bucks! You know all this stuff… Thought he typed with an accent, but wuddun’t shore… now I guess I knowz what ferr… :biggrinn:

Send that sucker to Ernest Rowe! Mine shot very well and was accurate… I had a failure of the firing valve. Evgeny sent me a new valve stem, but that did not fix it… I boxed ‘er up and sent it off to Ernest for a repair and full tune… WOW! I just thought it shot well and was accurate… Dang thing is amazing now!! Like I got a new gun… :8: :8:

:hoot:

Post your results later today. All this may be academic.

If not…you are not alone in your effort to get this gun up and running. This sport is WAY too expensive to not have that gun running at peak efficiency.

Hoot:

I agree he did a great job getting all that done. It was just unfortunate that the regulator wasn’t fully addressed while things were apart.
He’s obviously capable of getting access.

I don’t see much point in waiting before testing a shot string. A very slow leak would not change the test results. Lead would still need to be fixed, but one could go ahead and test the regulator immediately.

are they going to reduce the price of the Vulcans at some point?

i see it is made cheaper and cheaper.
anti rot switch disappeared, then the AT vent grubscrew disappeared, then the multibaffle system disappeared.
the paint from the regulator disappeared?

to me it looks like the seat is too far away so it is not shutting. turn it in. lower the regulator setting. do it by the angle not by the lenght for heavens sake, the length measurement is for losers. it never works. you turn the locking knob and you are off by a lot. is there a diagonal hole on the end threaded bit or that also disappeared? :rofl:

try to make your reg work and start again with setting you hammer spring tension. i think it is letting the full fill through and the hst is too high in. chuck the rubber bit in the bin.

turn the brass bit in half turn/full turn(a lot), you may have to return back to it later and fine tune it, but need to see some regulation. when you are fine tuning the reg, 2-3degrees make 10bar or more change in output. much more sensitive than the cricket reg.
if you lower it too much power will drop a lot, so you will need less hammer spring, but later you can crank both up later one at a time. but first you need to get the reg working.
while you are in you can inspect visually inside the reg, o rings and the white seat.
i think it is just a setting issue the reg is set too high and when the brass bit imprinted it it is too close to the end of travel so it is open