Re: The big AeroCarb/AeroInjector thread
Posted: Mon Sep 19, 2022 11:32 amI ended up using the #3. The two hot spots, idle and wot, must be within the slide travel to avoid having to correct with mixture at idle after adjusting for wot. The controlling measurement is thickness ( in the orifice opening ). I found that approx. .083 is the wot thickness, and depending on the angle, which you can calculate, the idle sweet spot ends up wherever the distance between the two puts it. I made seven needles out of .125 drill rod and #7 ended up measuring almost identical to #3. I had a contact from a Onex in Florida who suggested the #3.
The steeper angle of the #3 does not mean it's richer, it only means the two sweet spots are closer together and can both be located within the slide opening. I had my needle set for wot with the mixture about half way out. That left me able to go richer or leaner from that setting. Richer for temp. reduction on climb out and leaner at cruise for fuel economy. I did not have to touch the mixture after landing for a 900 rpm idle and did not reset it until the next takeoff. With the #3 the idle spot ends up a little too close to the wot spot and I had to reset the slide travel for idle. It was trying to idle at 700 and didn't like it.
I had the needle adjusted 2 1/2 to 3 turns in from the starting line for the Aerovee. There must not be any play in the ball end of the needle holder. Mine had nearly a half turn of play. Using a marker pen is not accurate enough, I marked the bottom of the needle with a file mark. Nice and shiny, easy to see with a mirror, and an accurate starting point. 300 fun hours without a problem.
The steeper angle of the #3 does not mean it's richer, it only means the two sweet spots are closer together and can both be located within the slide opening. I had my needle set for wot with the mixture about half way out. That left me able to go richer or leaner from that setting. Richer for temp. reduction on climb out and leaner at cruise for fuel economy. I did not have to touch the mixture after landing for a 900 rpm idle and did not reset it until the next takeoff. With the #3 the idle spot ends up a little too close to the wot spot and I had to reset the slide travel for idle. It was trying to idle at 700 and didn't like it.
I had the needle adjusted 2 1/2 to 3 turns in from the starting line for the Aerovee. There must not be any play in the ball end of the needle holder. Mine had nearly a half turn of play. Using a marker pen is not accurate enough, I marked the bottom of the needle with a file mark. Nice and shiny, easy to see with a mirror, and an accurate starting point. 300 fun hours without a problem.