Tuning Q for the tech tuners

[vmaxpro]

Im working on another assisted ( balanced) valve. Ive got a .062 hole in a .118 valve stem. The vent hole exiting perpendicular to the center hole should I do a .062 or 4 - .031 90 degrees apart ( more strength). I feel that a .062 single hole could weakin the pin. Any thoughts? Will the .031 holes be too restrictive and dwell the valve too long? The other end of the valve is setup for mikuni jets.

 

[Motorhead]

I would do twin opposing holes over a single larger one.

As to dwell, pending what % of area your isolating and ratio your at ? The closing force required will be something needing fiddling with.

Just yesterday I redid one of my Balanced valves on my .30 cal Bottlerauder. It was chamber vented at @ .055" having a nice short snappy dwell and quite efficient. It did very well with 44.75g pellets but would not dwell long enough for heavier slugs.

* Posted over on the GTA, here is a copy paste on that conversation / thread. You may find info of use ?

Made up another balanced valve with a peek poppet & only .042" chamber vent ( Extend dwell a bit longer )

Previous valve was very snappy and proved very efficient BUT WOULD NOT launch heavier pellets or slugs yielding more power even when raising Reg pressure .. Dwell issue was my thoughts.
With the original valve in rifle it would shoot @ 94/95 fpe with 44.75's and when something heavy like a NSA 61.7 grain slug was shot the power fell into the low 80 fpe range In spite the 700mm barrel.
Increases in poppet lift Via Buffer adjustment just made rifle use more air w/o any speed increase .. SO as set where no more power in gained via lift we have our most efficient / Power tune in place.

* Took rifles action apart and swapped valves, leaving hammer, spring & transfer specs unchanged.

Started at @ 1800 psi and rifle was cruising along at @ 96 fpe with a JSB 44.75 gr. Which was very close to the other valve removed .. So here no gain and a loss too using more air "As-Set"
As set up the muzzle blast was a tad more than previous as expected. Had purposely INCREASED the valve dwell to push more weight so no surprise there

So next we introduce some weightier slugs and see if the increased dwell at valve equated to better performance than original valve ?
Adjusting nothing else yet .. Now the 61.7 grain NSA's are knocking on mid 90's FPE

but still less than a 44.75 pellet ... bummer !
Ok time to put in some more poppet lift at the buffer adjustment. as we take 1/4 turn increases it wakes right up ( Where previous valve flat lined no matter adjustment ) and within @ a turn more on poppet lift screw we're smoking the 61.7 grain NSA's at @ 910 fps for an impressive 113fpe !!!

Needing to know where other slugs or pellets now shot with rifle obviously breathing better we try em ...

NSA 49 g @ 985fps at @ 105.5 fpe
NSA 60.9 @ 915 fpe at the similar 113 fpe
JSB 44.75 pellet @ 1023 fps at @ 104 fpe


So yes we found more dwell from the balanced valve that equated to extracting more power with the longer barrel ... It uses more air TOO !!! But hey it's a .30 cal so why baby it .. let it Roar