DON'T use Simple green! I just learned it attacks Aluminum.
I would use [
http://store.yahoo.com/cgi-bin/clink...30553.html]303 Cleaner[/url] This stuff works VERY WELL! Just make sure you cover all wires, computer boxes, and anything else affected by water with aluminum foil or plastic trash bag.
Use a small paint brush to get into small areas and rinse with lots of water. Here is an article on engine cleaning.
Engine detailing
Enjoy!
Jon