05-27-2016, 10:57 AM
On the face of the rev counter 6 o'clock position it will have RVI or RVC.
RVI tachs are often called impulse tachs. They are wired in series with current flowing through the ignition coil. They do not actually "touch" the ignition system. A loop of wire (either inside the case or literally looped on the back) inductively couples current pulses flowing through the ignition system wiring to the "counting circuit" inside the tach.
RVC tachs are a later, more modern design. They use a single sense wire connection to the "low side" of the ignition coil. They count the voltage swings between 0V and 12V each time points open and close.
RVI tachs are often called impulse tachs. They are wired in series with current flowing through the ignition coil. They do not actually "touch" the ignition system. A loop of wire (either inside the case or literally looped on the back) inductively couples current pulses flowing through the ignition system wiring to the "counting circuit" inside the tach.
RVC tachs are a later, more modern design. They use a single sense wire connection to the "low side" of the ignition coil. They count the voltage swings between 0V and 12V each time points open and close.
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