"Charles S" wrote in message
nk.net...
I have seen auto mechanics use an unlit propane torch at a very low
setting.
Directing it around the gaskets of a running engine, causes a very
noticealbe RPM increase, should a leaking intake system be present. One
has
to be aware to keep the propane away from the normal fuel air intake. I
don't know if this system of testing would be proper in an aviation
instance, where the prop wash may interfere. Maybe, feeding the propane
very close to the area to be checked, in small plastic tubing may help.



That big fan on the front of the aircraft engine keeps blowing the propane
away. Anyway this works best with a lean burn engines where the additional
fuel seeping in through the intake leak moves the mixture toward best power.

Bill Daniels