nomocom
Well Known Member
Our local EAA chapter bought a boroscope for the tool crib, the $350 Vividia unit available at Spruce. For the first time, I've got very nice photo's of all the valves. Per the Mike Busch valve talk (EAA webinar), what we want to see is concentricity of heat signatures on the face of the valve. There is one exhaust valve that shows a less than ideal heat signature.
This cylinder had a high resistance spark plug showing some fouling. The valve face will be watched, but in the meantime, it would be nice to know the valve rotator is doing it's job.
Anyone have a favored method for confirming the valve rotators are working? Or perhaps I should be less concerned about that and just do the SB for valve stem clearance?
A friend showed me a severe failure, a O-360 parallel valve cylinder from a certified Piper. The exhaust valve head came off the stem and bounced around in the chamber. I had assumed these aviation engines are non-interference. Do I have that wrong? What happens that a valve head can break off? Interesting, NTSB SEA05FA097 discusses a failure mode when an exhaust valve becomes "over-open" due to the valve train continuing to operate, without the pushrod and rocker arm in proper alignment. Still, even when finding the valve stuck in an over-open position, they don't mention valve and piston interference.
This cylinder had a high resistance spark plug showing some fouling. The valve face will be watched, but in the meantime, it would be nice to know the valve rotator is doing it's job.
Anyone have a favored method for confirming the valve rotators are working? Or perhaps I should be less concerned about that and just do the SB for valve stem clearance?
A friend showed me a severe failure, a O-360 parallel valve cylinder from a certified Piper. The exhaust valve head came off the stem and bounced around in the chamber. I had assumed these aviation engines are non-interference. Do I have that wrong? What happens that a valve head can break off? Interesting, NTSB SEA05FA097 discusses a failure mode when an exhaust valve becomes "over-open" due to the valve train continuing to operate, without the pushrod and rocker arm in proper alignment. Still, even when finding the valve stuck in an over-open position, they don't mention valve and piston interference.