LOP/ROP Measurement Q

When someone says, for instance, 30 degrees lean of peak, how is that measured? Is it 30 degrees LOP for the 1st cylinder to peak, or the last? Or the average? Something else?

For LOP operations, it's measured from the last cylinder to peak. For ROP it's the first to peak.

Depending on your engine monitor. Any digital monitor that is on all cylinders will tell you how many degrees LOP each cylinder is. Everyone states their operating conditions their own way. No one answer is correct. I typically average them when discussing where I run; however, in operation I consider which one is closest to the red zone.

Try this, lots of good info: https://www.advancedpilot.com/freesignup.php

Lots of good articles on AvWeb by John Deakin, as well.