In order to prevent dinging the tubes up or ruining them with pliers, you use a special tool, some people make their own with a piece of thin wall 7/8 inch tubing and a bolt, William Wynne demonstates one he made in his disassemby video. I could have made one like that but it would have taken more time to get the welding gear out, go get gas, practice up again, etc etc, so I ordered one from Clark's Corvairs. The head piece of 7/8 rotates, so it's better than one I would have made and I can tell you that the rotating aspect makes it much easier to use than a welded one because you can work it around the exahust manifold tubes and the bottom of the case easier. Here's a picture:
