Preheat oven to 350 degrees F (175 degrees C). Grease and flour 4 loaf pans.
In a medium bowl, mix together flour, salt, baking powder, baking soda and cinnamon. Set aside.
In a large bowl, combine sugar, oil, eggs and vanilla. Beat until smooth. Add flour mixture, and beat until smooth. Fold in walnuts and grated zucchini.
Divide batter into 4 well greased loaf pans. Bake at 350 degrees F (175 degrees C) for 60 minutes or until toothpick inserted into middle of cake comes out clean.