AviationBanter - View Single Post

**Cubdriver** · May 17th 07, 10:50 PM posted to rec.aviation.piloting,rec.aviation.student

On 16 May 2007 07:50:51 -0700, wrote:

Turning a prop backwards during hand-propping reduces the
mixture ratio in the cylinders if the engine has been overprimed. Air
is drawn through the exhaust and will absorb the fuel, carrying it
back through the carb and out. The carb will often drip fuel during
such an event.

That might explain an event that startled me at the time. While being
propped in hot weather--unsuccessfully--I was strapped in the rear
seat of the Cub, when the mechanic came by and said, "Your engine is
on fire." He leaned close to the cowling (the engine is visible
through the iconic J-3 cowling "ears"), gave a puff, blew the fire
out, and went on his way without further comment.

Blue skies! -- Dan Ford