Roll out the pie crust. Place it in a 9-inch pie plate and crimp the edges.
Pierce the bottom several times with a fork. Then line with with foil or parchment paper. Fill with pie weights or dry beans.
Bake for 10-12 minutes or until it's a light golden brown.
Remove from oven, remove the weights and allow to cool. Drop the oven temperature to 350°F.
Meanwhile in a large saucepan stir together 1¼ cups granulated sugar and the flour.
Separate the eggs, placing the whites in a really clean large bowl for the meringue.
Add the 3 egg yolks and sour cream to the sugar and flour mixture in the saucepan. Stir in the raisins.
Cook over medium heat, stirring constantly until the mixture is thick and bubbly. Turn off the heat but leave the mixture over the warm burner to keep it warm.
Add the cream of tartar to the egg whites and beat on medium heat until really frothy.
Start adding the remaining half cup of sugar about a Tablespoon at a time while beating the egg whites. Once all of the sugar is added, turn the mixer to high speed and beat until the meringue is glossy and holds stiff peaks.
Spread the warm raisin filling mixture into the pre baked pie crust. Smooth it out. Spoon meringue over the top of the filling, being sure to spread it all the way to the edges of the pie. You want to seal the whole pie.
Bake at 350°F for 15 minutes. Cool at room temperature for 1 hour then chill for at least 3 hours before serving.