Mercury - Ignition Rotor Prestolite Conventional Ignition Marine-Grade Composite 9089T. Overview. There's a certain confidence that comes from turning the key and hearing your engine fire instantly-no hesitation, no stumble, just a clean burst of power. That's the kind of reliability boaters depend on, especially when you're running an older but well-kept Ford or General Motors marine engine. The Quicksilver 9089T Rotor plays a quiet but essential role in that moment. It keeps your ignition timi