Preheat oven to 350 degree F. Grease and flour a 10-inch fluted tube pan. Set pan aside.
In a medium bowl combine the cake flour, baking powder, and salt; set aside.
In a large bowl beat the softened butter with an electric mixer on high speed for 30 seconds. Beat in the 2 cups granulated sugar, vanilla, and lemon oil until fluffy and light, about 4 minutes. Add the eggs, one at a time, beating 20 to 30 seconds after each addition.
Alternately add the flour mixture and buttermilk to the butter mixture, beating on low speed after each addition and starting and ending with flour. Beat just until combined. Using a wooden spoon, stir in lemon peel and the 1/2 cup juice. Stir in pecans. Spoon batter into prepared pan.
Bake for 1 hour or until toothpick inserted near the center comes out clean and the top springs back when touched lightly. Meanwhile, for glaze, in a small saucepan heat and stir the 1/4 cup granulated sugar and 2 tablespoons lemon juice until sugar is dissolved.
Let cake stand for 10 minutes. Invert cake onto wire cooling rack set over a shallow baking pan. Poke holes in the top of the cake with a toothpick or wooden skewer. Spoon glaze over cake. Cool completely. Makes 12 to 16 servings.