Mercury - SC1000 Tachometer 7000 RPM SmartCraft Analog Gauge Black Face 85 mm 79-8M0135641. Overview. The Mercury SC1000 7000 RPM Tachometer (79-8M0135641) gives you smooth, precise engine readings with a clean, factory look. The black face, white markings, and glass lens make it easy to read in any light, while the 85 mm (3-3/8 in.) fit makes installation simple. It connects directly to your SmartCraft network for accurate RPM feedback and supports SmartTow along with advanced SmartCraft featur