The most common method is to connect the tachometer wire to the negative (-) side of the coil. This is because the tachometer needs to sense the collapsing magnetic field created when the coil's current is interrupted. This interruption is what creates the spark.
Here's a breakdown:
1. Locate the coil: This is usually found near the distributor on the engine. It's a cylindrical component with two large terminals.
2. Identify the negative (-) coil terminal: This is often marked with a "-" symbol or is the smaller of the two terminals. Sometimes there is a wire already connected to the negative terminal of the coil that may need to be tapped into with a splice or a terminal connector.
3. Connect the tachometer wire: Carefully connect the wire from your tachometer to the negative (-) terminal of the coil. Use a proper connector, such as a crimp-on spade terminal and heat-shrink tubing, for a secure and insulated connection. Ensure that your connection is clean, solid, and won't short out.
4. Test the connection: Start the engine and check if the tachometer is working correctly. The needle should move smoothly and reflect the engine's RPM.
Important Considerations:
* Tachometer type: Factory tachometers from that era often have specific wiring requirements. Ensure the wire gauge is appropriate. You might need a ballast resistor in the circuit depending on the tach's design, but that's less common.
* Wiring diagram: If you have a wiring diagram for your specific year and model Impala SS, it's the best resource to determine the exact location and connection point. These diagrams often show the coil labeled clearly.
* Professional help: If you're uncomfortable working with car electrical systems, seek professional assistance from a mechanic. Incorrect wiring can damage the tachometer or even the vehicle's electrical system.
Disclaimer: This information is for guidance only. Always consult a wiring diagram specific to your vehicle's year and model to ensure correct wiring. Incorrect wiring can lead to damage.
