Cyberwolf, so let me get this right you're saying that the box needs to "breathe"? Well, I definitely did not allow for that as I sealed the tube to hole in the box with Goop, and doped everything.

I honestly don't notice any difference in this setup vs the stock hole in the backplate. I've flown it 2 weekends now. I would have expected some tuning diffs, but it seems to run fine except for the inverted stoppage at idle of course.

What if I got rid of the goop on the tube, and then poked some pinholes into the box? I thought the point of having the wooden box in the first place was to give a reservior which was immune to (abrupt) pressure changes inside the fuselage? I chose balsa because I thought it was important for it to VERY SLOWLY acclimate to pressure changes caused by weather and temperature differences (ie, from the basement to a hot car to outside air for example) a balsa box would allow that due to its porosity while a sealed bottle would not. I'm thinking poking holes would defeat the purpose of the box in the first place. Maybe only 1 small pinhole would do it?

One should keep in mind that in my plane (TOC Yak 33%) the pressure seen in the cowl is probably very close to the pressure in the entire fuselage as the firewall and engine box bottom have been cut to clear the carb and other installation features. The carb really isn't IN THE COWL as it sits so far to the rear and is exposed to the same air as my box. The cowl just serves to scoop all the air and at one point I convinced myself it ws causing a problem when inverted due to a wierd turbulence situation due to the angle of the incoming air and the orientation of the motor/carb etc.

When you installed your bottle as you say, did you definitely experince the inverted idle stoppage and see it cured by your installation?