For a lot of years, GM provided a tool to dealers to pack rope seals into the engine block and the rear main cap. Service manuals used to illustrate its use . It's simply a round piece of metal with a handle that's the same diameter as the seal surface of the crankshaft. I had a junk 4" piston handy that was a bit larger than the stovebolt seal, and a lathe, so I turned it down to 3 7/8" to match the rear crank flange and added a piece of 1/2" round stock for a handle. A simple rolling motion pre-forms the seal in the groove to the exact shape of the crankshaft, then it's cut off according to the procedure recommended by the seal manufacturer. They even provide a small box cutter and trimming guides with the seal. The 1/16" roll pin that's added to the lower seal groove is probably redundant, but we installed it as well.
Jerry
