Here's the SKF sleeve that fits a stovebolt crankshaft:

www.skf.com/us/products/industrial-...leeves/skf-speedi-sleeve/productid-99387

It's a 3 7/8 inch sleeve (3.875) that slightly increases the diameter of the surface it's installed on, and makes the seal grip the shaft a little tighter. It also is made of stainless steel, which is more rust resistant than the original crankshaft material. The raised lip is intended to be removed after the sleeve is installed, but if there are no clearance problems involved it can be retained to act as an oil slinger to help keep the seal from being flooded with oil that escapes from the main bearing. Using a small amount of red Loctite during installation can also be done to assure a tight fit.
Jerry

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