Too much air will cause "huffing". You'll know what that is if you experience it. If the flame won't stay on the end of the tourch you need a better flame holder. You can use any kind of center drilled cross-hairs setup you can think of but it needs to be about an inch back of the front edge of the burner tube and not be too restrictive. Alternately use a conical or stepped expansion cone on the end to hold the flame. Never got the twelve to one ratio thing to work for me. Had to do something more dramatic. All said and done though, you can't go wrong with a Rex prebuilt ventury burner. Don't say I didn't tell you so...
GA