ORIGINAL: Silversurfer
One thing at a time. Changing a bunch of things at once and you don't know what the fix was. If you need a balsa box, which I rather doubt, it would be a very small hole. You probably don't even need to run a tube, just deflect air from the opening.
Once again, have to agree with SS! Remember in one of my earlier posts about the 4.2, the problem was taken care of on one engine by just putting a plywood baffle in front of the carb. Had I known about it at the time, I'm betting that SS's plastic cap fix would have also worked. There are several methods to take care of this problem and they can all work for certain applications. Simple is probably best. As for the box, if you need it a pin hole is probably enough. Heck, the balsa by itself is probably pourous enough without any hole.