About this episode
Bennett contacted me awhile back to see if I could lap an exhaust valve for him.
The #4 exhaust valve showed a very uneven appearance when viewed with his borescope.
Bennett flew in to KSHD one morning and we got started.
Before lapping, we checked the cylinder compression and it was 29/80… not good.
Here’s what the valve looked like:
We got to work and lapped the valve.
When we were happy with the progress, we reinstalled the exhaust valve in the valve guide and installed new valve springs and a new rotocoil, to help ensure the valve would rotate properly and provide the best possibility for a good seal between the valve and the seat.
After running the engine, we rechecked the compression, and were very pleased… it was 74/80!
Amazing!
But there’s more…
Several weeks later, Bennett emailed me, and here’s what he said:
“Dean, I am so excited I am emailing from my hangar… Looks like lapping worked great! After one flight down to Florida and back… about 3.5 hours each way, the #4 exhaust valve looks vastly improved. See before and after pics attached. Much thanks!”
And here are the before and after photos he sent:
BEFORE:
AFTER: (and keep in mind the following photo was after only about 7 hours of engine operation.)
