Added a orfice to the fuel bypass line. This line allows the fuel pressure to bleed off after engine shut-down and suposeably improves air bleed if air is ingested into the system. I had bought a orfice fitting from Andair but it did not include a orfice and was not threaded for one. No mention of that on there web site. I couldn't find a way to drill the tiney .012 - .024 hole hole. I ended up buying a orfice fitting from SkyTek made for this engine. Removed Andair fitting, Installed Skytek fitting. The orfice dia is less than .021"