by Onex107 » Sun Feb 09, 2020 3:03 am
I had the same problem with the 2 and 2 1/2 needle. But, by filing on a 2 1/2 you are really just changing it to a #3. You can calculate the angle of the needle. Just measure the thickness/rod diameter and the thickness at a known distance down the taper and do the trig. The needle should be .125 in dia. If it's undersize it could run a little richer than mine. The difference between the two needles are in minutes of a degree. Before you start filing, try the #3. I think you will like the way it idles after setting up the wide open. For my Aerovee, I mark the needle, on the bottom, with a sharp file. The shiny mark is easier to see and more accurate than a black marker line. But before you put the needle in, see how much play you have in the ball socket. The 3/8 X 16 set screw gives you .060 movement for each full turn. My ball socket had nearly a half turn of play and you will adjust in half turns or less. Tighten it up. I bring my file mark out to the edge of the slide and go 2 1/2 turns further. At this setting I can manage the EGT and CHT temps with half the movement of the mixture. A little richer on climb out to cool off #1 and a little leaner to get back to the 1200-1300 range for cruise. I don't touch the mixture from one flight to the next after that. I'm at 285 hours and I haven't touched the AeroInjector since the initial setup. I did go through all the needles until trying the #3. They all had the bad idle problem.
OneX 107
N2107X