The seal you're referring to is made by "Best Gasket". It's the next best thing to an original equipment old stock rope seal, which contained a miracle fiber called (GASP!) "asbestos". Since that material has been found to cause people's offspring to be born naked, and simple possession of a few fibers of it is punishable by 30 days in the Electric Chair, the Best Gasket seal is the only thing that approaches the effectiveness and reliability of the original seal.

If the engine is removed and disassembled for a general overhaul, there's an alternative approach. The back of the engine block ahead of the flywheel can be machined for a full circle lip seal similar to what's used to seal wheel bearings, only much larger. The back of the stovebolt crankshaft has a seal diameter of 3 7/8 inches, and a lip seal can be fitted to a counterbore cut into the block and rear main bearing cap. The counterbore is 4.750 inches in diameter and .375 inches deep. This eliminates the rope seal and positively stops the leak.

The National brand 417210 seal or an equivalent item with the same dimensions works well. I machine all the engines I rebuild for that seal.

https://www.motion.com/products/sku/01315653

Good luck!
Jerry

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