Quote Originally Posted by roadster32 View Post
Roger I can't honestly see where doing that way you would ever get a nice corner and keep the 4 sides nice and flat
Your absolutely right. I had to make a 1/4" plate anvil the width of the tube ID, with rounded corners, that I clamped into the vice. On my header flanges the perimeter of the port is equal to the OD circumference of the 1.75" primary tubes, so that when formed the tubes slide into the flange. Not sure if yours are that way or not. With the SBF ports being taller than they are wide the tool you made would be a bit more "interesting" to form.