"In most Spintron testing, everything on the valve side of the rocker arm fulcrum (or pivot) is critical. Any weight saved here will usually result in an increase of limit speed with the same valve springs. Weight on the pushrod side of the fulcrum tends to be somewhat less critical because the velocities are so much less (less weight must be started, stopped and re-started into motion). Lightweight retainers and valve locks, valves and rockers are always the best targets for weight reduction as long as they are reliable. A part may be considered reliable if it lasts for one complete race, no matter how long or short. How practical this approach may depend on your racing budget."
By way of review As in the case of most component selections, compromise is almost unavoidable. When one area of concern becomes optimized, another likely is not. Striking that elusive balance between maximum power and optimum durability often boils down to having adequate information upon which to base decisions. Past experience, especially if someone else paid for it and is willing to share, frequently helps avoid repeated mistakes. Seek reliable information sources, ask a rash of questions and draw conclusions based on what you believe best fits your needs. And it's usually a safe bet to assume the manufacturer of a part is a more knowledgeable resource than something you read in a magazine. Well ... unless it was Circle Track, of course!