Half way through the rebuild of my 100-4 BN1 motor I've run into an unexpected problem. Apparently a previous owner modified the crank to take a GM seal, part number 460571. I didn't figure this out until I got my crank and block back from the machine shop and they returned the two semicircular halves of the seal with my old parts. Stupidly, I had not taken pictures of the rear main bearing block and the upper rear seal housing during dis-assembly. So I have no idea how the seal pieces were held in place. (The motor was not leaking at the rear main before I took it apart, so the modification was apparently working.)
New seals are available, but I can't figure out how they are held in place. They fit snugly on the crank journal and the flange surface that was machined, but they are not positively located by the bearing block or the upper seal housing, both of which appear to be unmodified. They would "float" in the original as-cast inner cavities of those two pieces.
Has anyone ever run into this modification? Any idea how the seals halves are held in place? Any help would be greatly appreciated.
New seals are available, but I can't figure out how they are held in place. They fit snugly on the crank journal and the flange surface that was machined, but they are not positively located by the bearing block or the upper seal housing, both of which appear to be unmodified. They would "float" in the original as-cast inner cavities of those two pieces.
Has anyone ever run into this modification? Any idea how the seals halves are held in place? Any help would be greatly appreciated.