The Valve Seat Recession Conundrum

In a recent blog posted on General Aviation News by Ben Visser, he made a point that poses a serious conundrum for the conversion to unleaded avgas: “The big problem here is that almost all of the aircraft piston engines out there need to be broken-in on 100LL, then they can be switched over to auto gas. But if they are started on auto gas when new, they will probably have exhaust valve problems.” The exhaust valve problems that Ben is alluding to is commonly known as “valve seat recession.”

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