Why is it my O-470 aircraft runs on 100LL without fouling
the plugs? Perry are you injecting crank case oil or mixing
two cycle oil with the fuel?
Paul Lamar
Damn, I was just at Columbia Airmotive yesterday!
I am doing both, mixing two stroke and injecting. Aircraft engines are
designed to deal with that crap, but some don't do so well from what I
understand. The O-235-L2C is notorious for lead plug fouling.
--
Perry Mick
It is hard to figure as they use rather weak magneto ignition systems.
Perhaps the crankcase oil has something to do with it.
As I recall there was something about synthetic oil having problems
with lead. What kind of oil are you using in the crankcase?
Paul Lamar
Could be. Yes I was using Mobil One and the "7" colder plugs when I had
the fouling really bad. But I also had fouling with the "9" plug. I'm
now back to using Pennzoil 20W50. I had the problem on my trip to KS and
back last July, and on my Copperstate trip, burning lots of 100LL.
Since getting back from Copperstate last October it's been only MOGAS,
and no more plug fouling.
Trip to Copperstate: stopped in Davis CA and tanked up with MOGAS.
Stopped in Victorville CA and tanked up with 100LL. Tanked up again
with 100LL at DVT Phoenix AZ. Stopped in Porterville CA on the way home
and tanked up with AVGAS 80. Climbing out of Porterville, suffered
power loss. Stopped in Medford OR, tanked up with 100LL, once again had
a power loss after takeoff. After I got home, this went on for a couple
weeks until I got all the 100LL burned out of the tank. I had to take
the plugs out a couple times and clean them. It would still foul even
with 50% mogas/100LL as I was diluting the lead remaining in the tank.
The whole experience made me swear off the stuff!
--
Perry Mick
So you have been using Pennzoil 20W50 since when?
Is that aircraft oil?
Paul Lamar
Since my last oil change, a couple months ago. The fouling was over by
the end of October 02 after all the 100LL was burned from the tanks.
Automotive oil.
Mike McGee says he runs his aircraft engine lean and experiences no
fouling. If the white color in my exhaust ports indicates lean
operation, then why would the plugs foul so badly? I'll try to get a
volt meter on the O2 sensor soon to see what the mixture really is.
When I suffered the power losses, the oil and water temps would rise to
abnormal levels. I think the engine was running only on the trailing
plugs, and we know Mazda has different timing on them. I would reduce
the throttle for a short time, then open again. Things returned to
normal and I was amazed how fast the temperatures dropped to normal.
After I got home and flew around close to home base the next couple
weeks, it got so bad that it wouldn't recover in the air, so I had to
land and remove the plugs and clean them.
--
Perry Mick
Custom Composite Props
mick@bridgingworlds.com
http://www.ductedfan.com
Well my theory on the synthetic oil not holding the lead my not have
validity as as I recall Tracy is using Mobile One.
You could try some aircraft oil in the crankcase.
Paul Lamar
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