I know that RSM and Aeroproducts have St style NVAs for Fox 35s. I was curious if anyone is  using the Brodak25/40(4mm) NVA in a Fox 35?
 I had to replace a broken needle valve(fox) with a packaged one(fox) in my box.  Engine won't run after prime is used up. I figured spraybar and needlevalve not compatible, although they looked the same. I know that 4mm =.160 and its pretty big for the fox venturi. I measured the fox spraybar @.132
thanks
Steve

The engine will pull fuel when choke flipped. It will run long enough to burn prime. I have cleaned the filter, new glo plug and checked fuel line for leaks. I suppose I could pull NVA assembly from another Fox 35 and see if that works.

Steve

Thanks
   Thats what I figured. Looks like buying replacements is the easiest(unless you  own a lathe).
Steve

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I'm not going to potentially ruin a piece I can use on another engine as is. Dug thru some parts and found some ST35 NVAs and an OS 10NVA. If neither of those work the plane gets an OS25(LA,FP,F) or awaits the appropriate part from RSM.
Steve

I have quite a few 1/2a, .35/.36 combat and stunt .35~.52  Fox/ OS/ ST/ K&B/ Enya engines where the venturi area and supplied NVA did not have the recommended open area

On Randy Smith's and Brett Buck's advice ---I DID NOT turn down the NVA diameter in a mill/lathe or drill press....each of their cautions was " too thin and liable to not tighten properly without stretching or breaking" so I followed the advise to file flats on both sides of the FAT ST NVA spray hole... to reduce / or perhaps...increase the flow volume

IMO this method works well ----BUT!!!

Ken Cook and I go back long way---- and he did NOT suggest hacking...he said...CAREFULLY ...RE RE-READ ---CAREFULLY sand and file the diameter down to increase the throat volume

I know if I had a good controllable method, I WOULD try his suggestion

I myself,, and I know Ken Cook uses,  Permatex Anaerobic Gasket maker --- just about every where a model engine needs an air tight seal

carefully applied---with the Anaerobic Gasket maker, YOU DO NOT need 8~14 Inch pounds of torque to seat a NVA too be air tight, and not move, due to normal vibration

So there is a way ...or many ways.... to achieve the suggested --or recommended ----Venturi/ NVA volumes... proper venturi hole and several different NVA----spigot, sprinkler, remote, local through pipe, filter, panty hose, wood spacer, sleeved down adapter....there are a lot of variations that do work

And just to acknowledge a facts or two

When a 16 YO kid, I had no such internet resource ---and the hints in magazines of the time were deliberately false so I was lost and failed a lot....

Since 2012 when I came back to the hobby----I have followed the Fuel, Plug, Prop, NVA/Venturi...advice.... pretty much lock step with Brett Buck, Randy Smith ,Dirty Dan, Ken Cook, and Jeff Dawson for all my vast array of glow engines

Must be blessed....3 years of playing airplane now--- and no burps, run aways, flame outs, or too much tinkering with props and fuel mixes

I have bought NVAs and Venturies from Tower, Randy Smith, Lee Machine, Brodak, Texas Timers, and Doug Galbreth all after the good advice on This and other excellent forums

None of this was possible in 1971 no matter what magazine you read

And Jim is the  winner!! I left the OS.10 NVA in, but opened it 6  turns. It started, pretty rich, turned the needle in 1 1/2 turns. I had been trying to run it with the Fox NVA @ 3 turns.
Thanks again everyone for the help.
Steve