In the bowl of an electric mixer fitted with paddle attachment, beat butter until fluffy; slowly add remaining 1 3/4 cups sugar, beating until blended, about 2 minutes. Scrape down sides of bowl. Beat at high speed another 2 minutes. Reduce speed to low; beat in eggs one at a time. Beat in vanilla, and alternate beating in flour mixture and sour cream in 3 parts until smooth.
Spoon 1/3 of the batter into the prepared pan. Sprinkle evenly with 1/2 cup pecan mixture. Top with another 1/3 of the batter; sprinkle again with 1/2 cup pecan mixture. Top with the remaining batter, and finish with the remaining pecan mixture. Bake until a toothpick inserted in center of cake comes out clean, about 1 hour and 15 minutes. Transfer to a rack; let cool in pan about 10 minutes. Run a thin knife around the outer and center edges of the cake to loosen; lifting from the center, remove cake from outer pan. Invert onto a plate. Slide a knife around the bottom of the cake to loosen; remove pan completely. Invert cake again, nut side up, onto rack. Let cool completely before serving.