Important Note: Consult your MSD distributor's instructions. The following is general advice and might not apply perfectly to every MSD unit. Improper wiring can damage your tachometer or other components.
Methods for Connecting the Tach:
1. Tach Output on the Distributor: Many MSD distributors have a dedicated tach output terminal. This is the easiest method. Look for a terminal labeled "Tach," "Tach Output," or a similar designation on your MSD distributor. This terminal will provide a signal directly compatible with your Auto Meter tachometer. Connect a wire from this terminal to the tach input terminal on your Auto Meter unit. The wire should be a shielded wire to minimize noise.
2. Using the Coil Negative (-) Wire: If your MSD distributor doesn't have a dedicated tach output, you can often obtain a signal from the negative (-) side of the coil. Caution: This method can be noisy, particularly with some ignition systems. You might need to add noise suppression components or use a properly shielded wire if you use this method. The wire from the negative coil terminal is connected to the tachometer input.
3. Using an MSD Tach Adapter: MSD offers tach adapters designed to interface with their ignition systems and provide a clean tach signal. These adapters often filter out noise and provide a more reliable signal to your tachometer. This is the preferred method if you're having trouble with noise or inconsistent readings using the previous methods.
Wiring the Auto Meter Tachometer:
1. Power: Connect the power wire from your Auto Meter tachometer to a switched 12V source (only energized when the ignition is on).
2. Ground: Connect the ground wire to a good chassis ground.
3. Illumination: Connect the illumination wire to your car's running light circuit for night-time visibility.
4. Tach Input: This is where the method described above (distributor output or coil negative) comes into play. Connect the appropriate wire to the tach input terminal on the Auto Meter tachometer.
Troubleshooting:
* No Reading: Check all connections. Make sure the power and ground connections are secure. Verify the tach signal wire is correctly connected to either the tach output on the distributor or the negative coil terminal (depending on your MSD unit and chosen method).
* Erratic Reading: Excessive noise is the most likely culprit. Try shielding the signal wire, using an MSD tach adapter, or checking for faulty connections.
Before you start:
* Consult the wiring diagrams for both your MSD distributor and your Auto Meter tachometer. These diagrams will give you the precise locations of the terminals and wires involved.
* Disconnect the negative battery terminal before working on the electrical system. This is a critical safety precaution to prevent accidental short circuits or shocks.
Remember, electrical work can be dangerous. If you're uncomfortable working with automotive electrical systems, it's best to have a qualified mechanic perform the installation.
