I've only had 2 incidents of plug fouling. The first, ironically, right
after I had asked my stage 3 check instructor if I should lean during taxi.
He said no. A few minutes later, I learned to clear my first plug. I
remember using runup power and just leaning aggressively. No CHT or EGTs
available. That was in a C150.

I had a real bad mag drop a couple of weeks ago in my Tripacer. My brakes
were a little on the weak side and, being that it's a hand brake, I couldn't
go higher than 1800 without starting to roll. I ran it up (1800) and leaned
until It was barely running smoothly (probably lean of peak). I did this
twice for about 30 seconds each. There were planes waiting behind me and the
second time didn't get it, so I pulled off the taxiway and repeated the
procedure for a full minute nad that got it. Had that not worked, I wasn't
going flying that day.

I don't think there's a real limit. If I had toe brakes, I might have tried
a higher power setting. Even now, in my TP, my brakes are back to full
strength, I would have tried as much power as the brakes would hold.


Just my $.02-and worth every bit of it. :-)

mike regish

"Roger Long" wrote in message
...
I can't remember where I "learned" it but I always thought 1800 RPM was the
limit for ground running leaned to clear plugs. I had a really bad one
yesterday with 250 RPM drop. I taxied back to the shop and they said to
try full throttle before pulling the plugs.

It worked but running the engine full power (near sea level) while leaned
for best power and peak EGT with minimum airflow for the minute it took
seems pretty abusive to me. Maybe you can get away with it because the
CHT's have not yet risen to max.

Any thoughts? What were you taught?

--

Roger Long