Valve / Valve stem

[angrybear]

Just to help me get my head around it, what matters most with the valve,
is it the length of the waist, the diameter of the waist or a bit of both ?
Also how critical is the valve stem O ring seal ?

I ask because I've got 3 stems, 1 x Dr Bob std, 1 x Dr bob Hi-flow & one unknown that has a longer waist than either, but is a fraction thicker (0.2mm)
Bob's Hi-flow stem seems very loose so the O ring won't have much, if any, seal.

[Ca_Varminter]

It all depend on the power level of your Rapid.....
If it is a 12 fpe..... longer thinner waist- high flow will help of efficiency..
But for High Power-FAC  These valve stems will help!!


Then there is my Titanium Power Valve stems....


The purpose of the small O-ring is slow the release of High Pressure Air when you shoot your Rapid!
It will cause a "Pop" sound when you shoot your Rapid!!

Hth,
Stuart

[Squinty]

Kev tailors the tails of  his stems so that the leading edge doesn't  block the top port when fully open and reduces the diameter from tail to top-hat to 2.5mm for high flow applications.

I've found a slight resistance on the o-ring about the right fit, just enough to stop the stem from dropping out.
Too much and the o-ring must grab under pressure and slow the valve?
Nowhere near an expert but I've picked up a little experience listening to the shot cycle

I ordered a pack of stem o-rings (BS607)  as I'd collected a few valves that needed refreshing .. I found that stems and bodies varied by more than just wear.
Some were tight, some loose with the 'correct' size o-ring, some wouldn't interchange ie late MFR and earlier black plastic as well as having different overall lengths

Bucketboys valves have a 3mm stem straight through, he either fits the stem o-ring in the Peek valve body or machines the tolerances tight enough to do without on the metal bodies.
He said that increases mechanical efficiency by reducing drag as the o-ring is stationary allowing faster cycling...plus lighter stem/top-hat & short body.

[Dr Bob]

Don't think that hi flow is one of mine Stuart? Mine have two groves in them. For the record, Theoben's idea was the first grove was to take the shock of the air blast to save the lower O ring. If you have an O ring in both air can get trapped between the two and slow the valve closing.

Bob

[Ca_Varminter]

Hi Dr Bob,

That is my Hi-Flow design....
Titanium of course....


Here is my latest Hi-Power design....
Short Stainless Valve-body. Delrin lined, precision reamed.
Titanium Valve, no O-ring!!


Stuart