I pulled the engine out of a Poulan 42 that run good and found the needles set to; High 1/2 turn and low 2 1/2 turns. I now have it in a plane and end up with about the same setting. But the high side doesn't seem to make much difference till it's screwed way out or almost all the way in. I have cleaned it and put in a new diaphram and pump kit. Checked and set outlet needle height. Also they are the same design. Not the usual long taper on the high side. Can I replace the high needle with something else and gain some adjustability? thanks