Preheat your oven to 350°F (176°C). Lightly grease two 8" cake pans with oil and cover the bottom of the pans with parchment paper (optional). Add a handful of flour to the pans and rotate the pans to coat with flour to prevent sticking. Shake out excess flour.
In a small mixing bowl, whisk together 2 ½ cups all-purpose flour, 4 teaspoons ground cinnamon, 1 teaspoon salt, 1 ½ teaspoons baking soda and set aside.
In a medium-sized batter bowl, whisk 4 large eggs, 1 teaspoon vanilla extract, 1 ½ cups granulated sugar, ½ cup sourdough starter discard, and 1 cup vegetable oil on until fully combined.
Pour the dry ingredients into the wet ingredients and stir them together using a spatula until combined. Fold in 3 cups carrots, ½ cup raisins and ½ cup chopped pecans.
Pour the batter evenly into the cake pans and bake for 35-40 minutes or until a toothpick inserted into the middle comes out clean.
Remove from oven, let cool for 20 minutes before transferring the cakes to a cooling rack to cool completely before frosting.