Our marine dealer installed an MSD CD ignition on our 1990 7.4 Bravo 1 to provide a rev limiter and to cure some hesitation problems while pulling skiers and wakeboarders.

The ignition is working perfectly, however now my tachometer is way off. At idle, 550 RPM the tach shows 800 RPM. At the rev limiter setting of 4600 RPM which is the factory recommended RPM for this engine, the tach shows 5500 RPM. Any thoughts will be appreciated, Charles

What are you using for reference? Installing ignition should not change the tach. Some of the tach's have a 4,6,8 switch on the back, some have a pot for fine tuning.