the end of the jet is at the air hole pretty much the same as Tony's design. I made the jet on the CNC mill so there is no way to put it in backwards. I have jets in three different sizes from .2mm to 1mm and it does not make a lot of difference which one I use other than the larger it is the harder it is to adjust. Presently I am running it directly off from a canister of isobutene camping stove fuel so that pretty much eliminates tank problems. Sliding the burner tube so that the air hole is beyond the end of the jet and even actually sliding the burner tube a slight distance beyond the jet does not seem to make much difference. I am not in the shop today but I will work on it some tomorrow. Maybe it is time to move on to something new for a while.