OK... my original post wasn't clear on the dieseling. It doesn't *normally*
diesel... only when I shut it off with the mags. Of course, I rarely do it, but I
discovered it one time when I tried. I was initially disturbed by it, but if you
think it though, it's a pretty tough situation to keep the fuel from igniting. Very
hot cylinders, very low RPM means very high MP even at idle setting. At the dieseling
RPM (100 or so), the MP will go up to 25", even with the throttle at idle. That
means essentially "full throttle," but a 5-10x longer *time* than idle RPM to
encourage the fuel charge to ignite. Actually, compared to takeoff RPM, more like a
25x factor longer time.

Anyway, I've decided to go with the midrange plugs (UREM38E). If they foul,
I'll clean them more often and/or change them back to hotter.

-Cory

Denny wrote:
: No engine can diesel without a fuel source... If it is dieseling, it is
: getting fuel... If it is getting fuel then the mixture rod is not
: cutting the fuel flow off completely... If the mixture is not cutting
: off properly then your carb needs a rebuild... Res ipsa loquitor...
: As far as the heat range, go with the recommended plug in whatever
: brand you like... If the current plugs are hotter than recommended
: either he was having lead fouling problems, or oil fouling problems...
: Or he got a heck of a deal on the plugs...

: denny - who's engines do not diesel on mogas...


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************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
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