I'm concerned about what I'm seeing in this borescope pic of a cylinder in my 1951 Kiekhaefer 7.5hp KE-4. What is the jagged stuff in the picture? Carbon buildup?
Looks like carbon buildup in the exhaust ports to me. You have to remember these things were run for years burning 30 weight non detergent oil . It shouldn't cause a problem unless it is built up to the point of blocking the passages .