"Mike Spera" wrote in message ...
Opinions on this one vary. I leave the valve where it is and switch
after burning off about 5 gallons (climb to 2500' plus 10 minutes of
cruise).

For my first tank switch, I like to be over something that I wouldn't mind
landing on or at a high enough altitude that having the engine stop would
not be too exciting of an experience... Subsequent switches, I'm not as
paranoid about...