Dan,
I just talked to Bruce about his engine. He said that he spoke with a Lycoming engine rep at Sun N Fun and was told that the max advance on the 390 with variable timing is 28*.
Incidentally, he has installed the SDS dual ignition system in it’s place, not the EFII system as I said earlier.
View attachment 20973
SPK. ADV. 20VAR - bottom row on data plate.