"Tim Hickey" wrote in message
...
I have a Zenith CH-300 with an O-320. I had a similar problem in the
beginning. I did as you have done, plus insulated the fuel lines,
installed a small heat reflective shield over the gascolater, and ran
a blast tube down to the mechanical fuel pump. Since then (about 1990)
I have run over 9000 gallons of mogas through the machine with out
problem. Although I will always let the engine (and the fuel pump that
is bolted to the case) cool between flights. If I know that I will be
doing flights without allowing a cool down period, I will put 100LL in
one tank, and take off on it.

Sounds like you have addressed all the issues that might arise from burning
"good" mogas. Obviously, nothing can insure failure from bad or contaminated
fuel, whatever the grade. I had insulated all my firewall-forward tubing
during the original construction, but insulation only delays heat, it
doesn't stop it. Sometimes I wish I had a thermometer which would monitor
under cowl temps. When it gets hot out, I can't believe the blast furnace
air that emits from the oil filler door. I remember one featured airplane in
Sport Aviation which had cowl vents which fell open whenever there was no
air pressure inside the cowl. Seems like a good idea to vent the hot air
when you shut down.

My Emeraude has both a mechanical pump and an electric pump. If I had to do
it over again, I would mount the electric pump near the rear tank, to insure
fuel flow. There is something to be said for the original design which had
nothing but gravity flow from the cowl tank along with a forward-facing tube
on the fuel cap. Sometimes simple is best.

Tailwinds,
Rich S.