Here is a very interesting article that I came across about fuels and additive Octane boosters.
Some of you with Weber Carbs and from what I have heard from the 4 bbl fokes, they have been experiencing fuel dribble after shutdown.
This article basically explains alittle about that and how to mix your fuel to get the right octane rating.
Enjoy
http://www.idavette.net/hib/fuel/index.htm