Detonation on takeoff is a "thing" when you have fixed timing with magnetos. Remember that with fixed timing you are trying to satisfy two masters - a large enough advance to give reasonable high altitude and lean performance, but not so much advance that you detonate at take off power. It just so happens that those two requirements are in almost perfect opposition. So in the certified world Lycoming has to play a very careful dance. With variable timing we can completely eliminate this sometimes razor edge compromise.
You dont need to find out what the margin is at high advance at takeoff because you should not be at high advance at take off. Thats a problem for the magneto guys.
WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.
Harmon Rocket II -SDS EFI
1940 Taylorcraft BL-65
1984 L39C - SOLD
RV-8 - SDS CPI - SOLD