Mercury - Distributor Cap Conventional Ignition PBT/PET Composite 9459Q1. Overview. There's something reassuring about turning the key on a MerCruiser engine and hearing it fire up instantly, no hesitation, no second guesses. That smooth, confident start comes from a lot of small parts doing their jobs quietly beneath the engine cover-and the distributor cap is one of the most important. The Mercury 9459Q1 Distributor Cap is built for the kind of reliability you feel every time you pull away fro