Shutting my Roadster off.

[ford-m]

Met a fellow "A"er who jumped all over me for doing the following while shutting my Roadster down. Told me I would ruin the carb and wear out the fuel shut off valve and cause stress on the motor. ????

This is what I do.
I turn off the fuel and let it run out of fuel if leaving it for any length of time like overnight in the shop or say I know I will be away from it for five or so hours.
If just running to the store to get milk or eggs I don't do this but for lengthy periods I do.
Am I doing any harm doing this ?

Michael