With throttle plates completely closed, 10-12% Then set air gap on the plates at 1/8" inch. This would be for stacked injectors for nitro cars running sportsman TAD. With a multiple injector set (4 sets) We set at 30% to start and end up a little higher according to air conditions and vary that, but a base to start is about 30%. This is at the shop on the test stand and the track, depending on where we're are at will be changed accordingly. With nitro being a different base fuel according to it's stoichiometric ratios and the fuel is mixed with Methanol, We can start there and use the pop-its (bleed offs)to tune the power band. The hat is almost shut with hardly any air flowing thru it because of the Oxygen we're supplying by the fuel.