Q: I am an Italian homebuilder of a Van’s RV-3. I read on the Internet that you are an expert of Lycoming and I want to impose on your kindness. I am ready to make the timing on my Lycoming O-290 D2 but there is a little doubt about the timing degrees because the O-290 is not a common engine in Italy, as it was used only by the Italian Army in a PA18. An AD issued in 1954 changed the timing at 18° (label on engine) to prevent detonation, probably with 80/87 fuel. If I use 100LL, will I have to change the timing? Many thanks in advance and sorry for my bad English.