Larry Shepard has written in many publications about them finding swirl properties in heads like all of the letter castings, such as X, O, U, J and so on. They were swirl heads before Chrysler even knew about it. It was a complete accident. I've always felt that was one reason why the small block heads were generally better than all the other manufacturers heads of the same era. Even being a smog open chamber, they got the job done.
