The Harley-Davidson Evolution engine, or Evo, is sometimes also called the Blockhead. It is an air-cooled, 45 degree V-Twin motorcycle engine manufactured by the Harley-Davidson Motor Company since 1984, with an 82 cubic inch (1,340 cc) displacement, replacing the "obsolete" Shovelhead engine, until 1999 when it was replaced by the Twin-Cam 88. Most analysts consider the Evolution to be the engine that saved Harley-Davidson from certain bankruptcy.
Wow, that Blockhead in in your 83 Harley FXWG has 400,000 miles on it!!! That's crazy!!!