Takeoff and climb will be the most noticeable performance loss, cruise as well but not as dramatic. If you have an engine monitor you can see it IF you know what the EGT traces looked like when it was good, and then later notice that a pair of cylinders on intake lobe peak later than the others. Less valve lift = less air going into cylinder = richer mixture = later peak. That was the case for me, anyway, when my first intake lobe started losing metal. I don't know what they would show if an exhaust lobe went flat...
In a Lycoming you cannot see the cam with a borescope, unless you remove a cylinder first and then look through the borescope.
In a Lycoming you cannot see the cam with a borescope, unless you remove a cylinder first and then look through the borescope.
