They are shoulder bolts, I made them myself on the lathe starting with a piece of 1/4" smooth rod, so I am the cobbler. Originaly yes they did come with an allen bolt, but you can't over tighten a rod end, it's just not possible.

The problem is not the bolts. It is the rod ends themselves. The ball is too tight in the nylon lining of the rod end. It is the way they are manufactured, made by Edelbrock.