Hoping someone could suggest a shop that has experience doing this procedure. I’m located in Coeur D’ Alene and my mechanic has not performed this procedure in the past. Any suggestions within the Pacific Northwest is appreciated. I received the below guidance from savvy after I sent them the Borescope images of my p ponk.

Here is valve lapping information (from Paul New's website):
https://www.tennesseeaircraft.net/2011/ ... e-lapping/
1. Remove rocker arm, rotocoil (for Continental), and valve springs.
2. Check for excessive wear in valve guide.
3. Apply valve grinding compound to edge of valve, working down through the top spark plug hole.
4. Attach a small piece of clear vinyl tubing to the valve stem using a small hose clamp.
5. Attach a piece of wood dowel rod to the other end of the vinyl tubing.
6. Chuck the dowel rod into a cordless drill.
7. Rotate the valve with the drill while pulling the valve carefully back against the seat, alternating in both directions.
8. If the valve starts to "chatter," stop immediately... time for more grinding compound... might take 30 seconds or more.
9. Examine the valve edge through the top spark plug hole before adding more compound. (Be sure bottom spark plug is removed, and wash the valve edge off, letting the fluid and compound run out the spark plug hole.). I use Avgas in a squeeze bottle with a 90 degree spout for washing the valve edge, but I'm sure there are other options, like an appropriate spray solvent.
10. After each lapping cycle and subsequent washing of the valve edge, you can clearly see the progress, or lack thereof.
11. Repeat the process until you have a nice uniform band of sealing area on the valve, OR, you determine the valve cannot be saved.
12. If it was successful, wash the cylinder out as well as possible, and spray some lube in the cylinder for piston ring lubrication.
13. Reassemble everything, and do a gound run.
14. Check for leaks and do a compression test... hopefully it came up quite a bit!

I’ve done this before with success. You have the instruction right there but use valve lapping tool. It attaches to the valve stem with a hose section. It’s like an old fashioned hand drill but goes back and forth as you turn the handle. It advances and retreats in a circle, three steps forward, one back. You can control the grind of the seat by how much you pull on the stem as you turn the handle. Our shop had it in the tool crib. You can probably get one at NAPA.
An electric drill may be too aggressive and quickly ruin a valve seat. I wouldn’t use one.
I would put a rag(s) into the cylinder to catch any valve grinding compound.
Like a surgeon keep track-two go in, two come out.
Use paper towels twisted into a rat tail soaked in a solvent inserted through the plug hole to wipe the valve and you can capture it to wipe the seat. Take your time, be judicious with the compound.
This is not rocket science. Your A&P should be able to do this.
They used to call this a south of the border valve job in less PC times.

The biggest problem with this is you're going to have a tough time getting the compound out of the cylinder. It's very abrasive and gets everywhere, especially if you try to use a drill on the valve stem. It's a bandaid fix and not necessarily addressing the problem, just the symptom. If it was mine, I'd pull the jug and do it right....you might be surprised at what you find. An easy estimate is that 99% of the time you actually disassemble the valve mechanism, you'll discover that the seat and valve face both need trued up before lapping, and more often than not, the guide isn't all that tight.
John

Have you tried Scott Olson up on Hackney? I'm pretty sure he can do it

I second checking with Scott Olson. Also try looking for a piston helicopter mechanic. They deal with valves on as a regular unlike fixed wing mechanics. They would have the tools and expertise to do this on the plane.

hardtailjohn wrote:The biggest problem with this is you're going to have a tough time getting the compound out of the cylinder. It's very abrasive and gets everywhere, especially if you try to use a drill on the valve stem. It's a bandaid fix and not necessarily addressing the problem, just the symptom. If it was mine, I'd pull the jug and do it right....you might be surprised at what you find. An easy estimate is that 99% of the time you actually disassemble the valve mechanism, you'll discover that the seat and valve face both need trued up before lapping, and more often than not, the guide isn't all that tight.
John

This. Found some real sloppy guides in mine with 650 hrs. Also found a cracked rocker shaft bushing.

Valve honing with a drill goes a lot faster than you'd think, and faster than you may want. Doing it by hand gives a groove free seat.

I cannot evaluate the land dimensions to verify things are inside the service limits with the cylinder on. It is easier to just pull the jug off if recession is a potential issue so it can be checked, and also to avoid cramming the borescope in and out and washing the land to verify you got past any pitting in the land.

I've seen experienced mechs do it in situ, however. I just don't want to know where the compound ends up.

I've done this a bunch of times with mixed results. Half of the times I ended up pulling the cylinder anyway because I couldn't be sure I had gotten all the valve grinding compound out. One of the first times I did this I missed or dropped some valve grinding compound in the cylinder where I couldn't see it and it ended up scoring the cylinder. Ever since I've been hyper careful to get all that valve grind out and even then I don't really like doing it. As someone else mentioned its really just a band-aid and chances are you'll have to pull that cylinder in short order anyway. For an extra couple hour's work for an R/I I just find it easier to pull the cylinder off and do it right.