How to Port & Flow Test Cylinder HeadsPorting heads is an art and science. It takes a craftsman's touch to shape the surfaces of the head for the optimal flow characteristics and the best performance. Porting demands the right tools, skills, and application of knowledge. Few other engine builders have the same level of knowledge and skill porting engine heads as David Vizard. All the aspects of porting stock as well as aftermarket heads in aluminum and cast iron constructions are covered.