That is very useful information. On our water cooled engines the only
time we'll see 350° is just before the engine siezes!
I believe that most of us understood that leaded
gasoline can lead to spark plug fouling. It turns out even with
the "Scavenger" compounds it apparently will still happened. See article
below:
I also read one report that address aircraft engine
effect. It basically said that if the CHT is not kept over 350F the
scavenger effectiveness is minimal. So this may be why aircraft
sparkplugs do not seem to foul as often as the auto plugs (higher CHT).
URL
:http://www.petroleumbazaar.com/MS/msappli2.htm
During combustion TEL (Tetraethyl
lead ) forms an oxide of lead which is not volatile and so should
tend to deposit on the combustion chamber, valves, spark plugs, etc. with
harmful effects. To counteract this. "Scavenger" compounds, such as ethylene
dibromide and ethylene dichloride, are mixed with TEL so that on combustion
more volatile compounds of lead are formed, resulting in most of the metal
passing out with exhaust gas. The TEL together
with the scavengers and a dye to indicate the poisonous nature of the compound
is known as "ethyl fluid".
Despite the use of decavenger compounds, it can
give rise to such difficulties as: sparkplug fouling, surface ignition,
exhaust valve failure and octane requirement increase.