Look ma. No lead deposits in my spark plugs

Ron Lee · #1 01-06-2008, 01:46 PM

After about 80-90 hours on a rebuild O-360, 9.5:1 pistons, carbureted, one mag, one Lightspeed ignition I removed the lower aircraft plugs to check them during my condition inspection. What was odd is that the normal lead deposits were missing.

My guess is that the port/polishing/flow matching that I had done on the Millenium cylinders, which now allows me to cruise at peak or lean of peak (<75% power), is responsible for this improvement.

N941WR · #2 01-06-2008, 05:12 PM

Funny, yesterday I pulled all eight of my NGK's (Duel P-mag setup) now that I have 85 hours on the plane and I wondered why I was worried. Not spec of led anywhere.

Electronic ignition is great!

Ironflight · #3 01-06-2008, 05:29 PM

That sounds great Ron!

I've always wondered what I am doing wrong....I've owned and flown Lycomings for thousands of hours of a few decades, and have never done any of the things people Say that you HAVE to do (lean on the ground, do a lead scavenging run before shutdown, etc...) to prevent fouling - and I have never lead fouled a lug, They always come out clean as a whistle. And yes, I'm running 100LL. My current engine is running with extended nose plugs (that's stock from Mattituck), and maybe that is why I get away with it...

Paul

Ron Lee · #4 01-06-2008, 05:56 PM

Paul, I have fouled plugs before (lower plugs) and almost always lean while taxiing (I sometimes forget). The Lightspeed does keep the upper automotive plugs clean. Maybe your plugs contribute to staying clean. I don't know. My lower plugs are fine wire aviation plugs.

While this may seem trivial to some, it is another preliminary indicator that the work I had done on the cylinders was justified.

I just finished putting in four cylinder probes for CHT and EGT and plan on getting better data of the consistency between cylinders as I approach peak EGT and then run lean of peak.

AlexPeterson · #5 01-06-2008, 06:30 PM

I run LOP in the air, and lean aggressively on the ground. Lightspeed on all plugs, and I do see little balls of junk in the lower plugs after 100 to 150 hours. top ones are clean. Sure is nice to just chuck them out instead of cleaning! I really hated that part of the annuals in the past. I burn a quart of oil every 8 to 10 hours.