Lead on exhaust valve

I bought a boroscope and decided to look at my exhaust valves in my IO-360 of 750hrs. I always TO ROP of course and do most of my cruising LOP. Go back to ROP in the descent. I tuned. My injectors with Don at Airflow Performance a few years back via his remote method of recording EGT’s. My EGT’s show in the mid 1400’s LOP. About 100 or so hotter than ROP. I was surprised to see what looked like lead balls all over the face of the valve. A thin consistent caked on layer of lead with droplets of lead around the edges. Although the valve had a concentric wear look and didn’t appear to be burnt anywhere(again, just looking) I couldn’t see colors....like a green to designate a burnt area. The spot in the middle of the valve didn’t have lead attached to it or at least not much. Is this normal to have this layer on the valve?

What you would like to achieve LOP is to bring your EGTs from peak to about 50-75* cooler than peak by leaning. The exact temp reduction from peak does depend on %hp, but no need to get hung up on it. Off hand, I think that you are not quite LOP. Have you seen the procedure from the GAMI website? Also, you may want to stay LOP in the descent and only enrichen once you are in the pattern or when the engine tells you. Despite owt you really can't hurt the engine at low%hp and lean. The worse that can happen is so lean that it quits, but it will not harm it. Again low hp demands.

https://gami.com/ look at the links at the top for articles.

hope this helps.

Ps. You may want to do a lean ground run for a minute before shutting down. We used to use about 1800 rpm and lean until the engine almost dies - it will be rough running. Hold for a minute, then idle for a few seconds and shut down. I think Lycoming has a letter about it, but this practice was done in the military with the IO360

Lead needs to stay hot to remain gaseous and scavenge. Lycoming exhaust valves commonly accumulate lead because they're sodium filled and transfer heat better than Continentals.

Aggressively lean for all ground operations and lean ROP for best power for a bit, then re-scope jug.

Normally the deposits accumulate around the valve stem which is cause for the Lycoming "wobble test" but they certainly could build on the face.

Pretty certain I'm LOP in cruise. I typically cruise just under 23 squared. Cylinders cool 30-40 degrees after leaning this time of year. About 7 Gal at 3,000ft.

Suggestions other than cruise sound interesting.

Yep you are LOP for sure at 23/23 and 3000. 23 squared ROP would be burning 8.6 to 9 gph.(I'm assuming you have a parallel valve IO-360-Bxx engine).

Hello Boyd. Yes, It's a paralell Superior Experimental IO-360 with the cold air sump. Injected. The airplane builder also went down to Coppell and built the engine during one of their shops. Just trying to figure out why there is so much lead on the face of the exhaust valve. The last two runs I kept it ROP and ran it hard to get the oil temp up. Maybe that was enough to "confuse" it. I guess I need to go run it LOP, run at best power leaned out and then scope again.
Tim Davie

I have been using TCP which can be had from ACS. I used it in another aircraft for 20 years and 3000 hours 360 lyc. I started running it in this 540 at around 600 hours. I was noticing a lot of lead balls and accumulation on the top of the pistons. The plugs come out clean, no,lead balls anymore. I run LOP

Interesting. I know the Rotax guys use it religiously.