Thursday, July 4, 2013

Advanced engine leaning techniques

On July 3, 2013, Mike Busch of Savvy Aviator fame, held an EAA webinar on engine leaning techniques, following up several other leaning sessions which are still available on the EAA website.

These are my notes from his talk, the most significant portion of which (to me) was his assertion that Lycoming now recommends mag timing at 20 degrees top dead center, rather than the 25 degrees recommended on -- in my case -- the data plate on the engine and the owners guide. My engine was purchased in 2008. We might be hearing more on this. Perhaps not.

The biggest impact on the way I've been leaning my engine, however, is I am now implored to stop using exhaust gas temperature to determine the peak. I've been making a big mistake. See the notes at the link for more.


  1. Link doesn't work Bob. 7-4-13

  2. Link works for me as well. Fascinating stuff -- I'm very thankful for your recap because I wasn't able to see the webinar in "real time" and EAA doesn't seem to archive them for members.

    I'm a big fan of Mike Busch, going back a decade and a half to when I was a CPA member and would read his articles in their magazine. I followed his AVweb column, Savvy Aviator posts, and EAA articles, but this 20 degrees BTDC stuff is news to me! I'm also surprised to hear him discount EGT for leaning, because every plane I've flown LOP has required finesse provided by that data to walk that fine line between LOP and engine roughness, even in aircraft with balanced injectors like the SR22.