How to Lap a Valve in situ Video by Mike Busch

[kortopates]

I've posted an article on how to lap a valve in situ before. This past weekend Mike had to do it and created this very good instructional video for the team on how to do it. He also had it posted on Facebook, so I thought I'd post it here too. Hopefully, many will find it helpful.

Mike shows how to clean the valve face at the end, but be sure to clean the valve and seat as best you can to prevent imprinting some of the compound into the seat. One would think all the compound would immediately blow out the exhaust but wouldn't want to take the chance.

Also don't recommend  rinsing the compound out/off (by spraying solvent or LPS) because all that grit runs into the cylinder and can find it's way to the piston rings. 

Can't say how likely either of these issues are but wouldn't want to risk it.

This is done without dropping the exhaust since on older/higher time pistons its not that uncommon that a stud comes out when pulling the exhaust nuts and all of sudden in your in for a much larger job. But with the exhaust off, its makes it much easier to apply the lapping compound and clean the valve face since you don't have to go through the spark plug hole.
 

Edited April 13, 2022 by kortopates

[Greg Ellis]

I watched the video yesterday or the day before when he first put it up on youtube.  I hope he follows up with a video on how the valve is doing after a few hours of flight.  It was interesting to watch someone do this.  There is another good video about this but it is all external.  Mike does a great job showing the internal aspect with the borescope.

[BobbyH]

Absolutely impressed with the quality of images from his borescope.  I probably need to upgrade mine.   Thanks for posting @kortopates, appreciate learning more all the time.  Although the video makes it look simple, cleaning the valve after grinding is a tedious process.  When Mike says it will take a few sticks to clean it, he is correct.

Bob

[smwash02]

5 hours ago, kortopates said:

Also don't recommend  rinsing the compound out/off (by spraying solvent or LPS) because all that grit runs into the cylinder and can find it's way to the piston rings. 

Can't say how likely either of these issues are but wouldn't want to risk it.

I've had the [mis]fortune of having to do this a few times.

I put a piece of flannel on some safety wire and doused it in fuel. I then put it between the seat and valve and rotated it a bit by hand. I repeated this cleaning a few times until it wasn't picking up any more valve grinding compound.

Edited April 13, 2022 by smwash02