Preheat oven to 350°F. Grease or spray with non-stick cooking spray a 9 x 5 inch loaf pan.
On a flat surface, shred zucchini on a box grater using the largest hole grating size. Transfer zucchini to a clean kitchen towel. Place zucchini in the center of the towel, spreading it out lengthwise. Roll zucchini up in the towel. Grasping both ends, and using both hands, twist the towel like you are wringing it out. Repeat wringing until little to no liquid comes out. Spread zucchini out on a dry towel until you're ready to add it to the batter.
In a large bowl, with the mixer set on medium, cream the shortening and the sugar until light and fluffy. Add eggs, one at a time, beating well after each addition. Add vanilla, cinnamon, allspice, nutmeg and sour cream. Beat on low speed to combine.
In medium bowl, combine flour, baking soda and salt.
Add the dry ingredients to the batter, beating on medium speed for one minute. Scrape down bowl as needed. Fold in zucchini, walnuts and raisins until well distributed.
Spread into prepared pan. Bake on center rack of oven for 1 hour to 1 hour and 15 minutes, or until toothpick inserted in the center comes out clean.
Allow to cool for 10 minutes on a wire rack. Remove from the pan and cool the loaf completely on the wire rack before slicing.