no, for real, i couldn't find it lol. i ended up with some scientific, stephen hawking-like definition of it.
i'm on howstuffworks right now. i'm a page into this one, so we'll see how it goes:
HowStuffWorks "Ignition System Timing"
the last page looks like it has a bunch of fun links on it:
http://auto.howstuffworks.com/ignition-system6.htm