Rotor tach working through the EIS system

[GyroRon]

Todd and anyone else using the EIS for a rotor tach. What is the number of teeth on your ring gear and what is the number you set your EIS to, to give you a proper reading. Mine was reading way too low, but I checked the number the EIS was set at and it was set at only 100 when I think it should have been set at 197. Help!

[ToddP]

I'll check next time I'm at the airport, there is a little formula you have to run, no big deal, I'll let you know.