Avidflyer2
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https://bmwmotorcycletech.info/valve-rotation.pdf
Here is an excellent article on the importance of exhaust valve rotation and the mechanics on how it is done.
TCM Continental uses the “Rotocoil” while Lycoming uses the direct acting method. Either method rotates the exhaust valve about three times a minute at cruise rpm. A valve that stops rotating is more prone to burning and or warping of the valve face. While using a borescope, look for a grayish area on the valve seat in the cylinder head while the valve is open. A gray area instead of a shiny dark ring is a sure indicator that valve is no longer rotating. Minor problems with the valve not sealing may be self-healing if the root cause is rectified quickly. This may mean replacing TCM’s rotocoil, or Lycoming’s rocker arm.
I read that ECI has an STC to install rotocoils on a Lycoming engine but I have not researched that completely.
Here is an excellent article on the importance of exhaust valve rotation and the mechanics on how it is done.
TCM Continental uses the “Rotocoil” while Lycoming uses the direct acting method. Either method rotates the exhaust valve about three times a minute at cruise rpm. A valve that stops rotating is more prone to burning and or warping of the valve face. While using a borescope, look for a grayish area on the valve seat in the cylinder head while the valve is open. A gray area instead of a shiny dark ring is a sure indicator that valve is no longer rotating. Minor problems with the valve not sealing may be self-healing if the root cause is rectified quickly. This may mean replacing TCM’s rotocoil, or Lycoming’s rocker arm.
I read that ECI has an STC to install rotocoils on a Lycoming engine but I have not researched that completely.
