I stumbled upon this pulley calculator....

[Krooser]

lots of good info here...

http://www.blocklayer.com/pulley-belteng.aspx

[RCJ]

They have a degree wheel template also,cool site

[Lizardracing]

Calculators are fun but I never trust them so I do math anyway. You never know when someone plugs in wrong figures. Including my own mistakes lol