Preheat oven to 350F
Grease 10-cup Bundt pan, or 10" tube pan (9"x4"loaf pan also works).
Cream the butter and sugar until light and fluffy.
Beat in the eggs one at a time, scraping the bowl occasionally.
In a separate bowl, whisk together the flour, baking powder, and salt.
Alternate adding dry mix and orange juice to the butter mixture, 1/3 at a time.
Stir in the orange zest.
Pour the mix into the prepared pan.
Bake the cake for 50 to 60 minutes, or until a cake tester or toothpick inserted into the center comes out clean.
Remove the cake from the oven and let it sit in the pan on a rack for 10 minutes.