Let eggs stand at room temperature for 30 minutes. In a large bowl, combine the flour, sugar, salt and baking soda. In a bowl, whisk the egg yolks, orange juice, oil and orange zest; add to dry ingredients. Beat until well blended.
In another large bowl and with clean beaters, beat egg whites and cream of tartar on high speed until stiff peaks form. Fold into orange mixture.
Gently spoon batter into an ungreased 10-in. tube pan. Cut through the batter with a knife to remove air pockets. Bake on the lowest rack at 350° for 45-50 minutes or until top springs back when lightly touched. Immediately invert pan; cool completely. Run a knife around sides and center tube of pan. Invert cake onto a serving plate.
For glaze, melt butter in a small saucepan; add remaining glaze ingredients. Stir until smooth. Pour over top of cake, allowing it to drizzle down sides.
