[Bob Bidonde]

The strength of the crankshaft material and its fatigue life are effected by welding, especially if the crankshaft is not heat treated to relieve thermal stresses after welding. Use the crankshaft as is without any additional welding.

The bolt is the primary reactant of tension from the centrifugal forces due to the counterweight. Although the tack welds do react some of the centrifugal forces, their primary purpose is to retain the alignment of the counterweight by preventing the weight from pivoting about the bolt.