Tachometer Signal Filter for GM Vehicles 1967–1989 – HEI & Aftermarket Ignition Noise Reduction

Tachometer Signal Filter for GM Vehicles (1967–1989) – HEI & Aftermarket Ignition Compatible

This tachometer signal filter for GM vehicles helps correct unstable RPM readings caused by electrical noise and voltage spikes from HEI and many aftermarket ignition systems. As original filters age, the tach signal can become erratic, slow to respond, or partially blocked—especially on factory-style tachometers.

Features at a Glance

• Helps stabilize tachometer signal on many classic GM applications
• Designed for HEI and many aftermarket ignition systems
• Helps reduce noise/spikes for steadier RPM readings and quicker response
• Color-coded wiring for straightforward installation
• Includes hardware, illustrated instructions, and troubleshooting tips

Compatibility Notes

• OEM-style replacement tach filter used on many GM-era tach systems
• Aftermarket ignition compatible (examples: MSD, Holley, Speedmaster)
• Installs between the tachometer and the signal source to help condition the tach signal

What’s Included

1. Tachometer Signal Filter
2. Installation hardware
3. Illustrated installation instructions
4. Troubleshooting tips

Vehicle Fitment

Commonly used across many GM vehicles equipped with factory-style tachometers from the late 1960s through the 1980s:

• Buick: Regal 1978–1987
• Chevrolet: Camaro 1967–1989; Caprice 1967–1986; Chevelle 1967–1971; Chevelle Malibu 1969; Chevy II / Nova 1968; Impala 1967–1971; Malibu 1967–1983; Monte Carlo 1970–1988; Nova 1970
• Chevrolet: El Camino 1967–1987
• GMC: Caballero 1978–1987
• Oldsmobile: Cutlass Supreme 1978–1987
• Pontiac: Firebird 1967–1989; Grand Am 1978–1980; Grand Prix 1978–1987

Troubleshooting FAQ

Will this help a tachometer that bounces or reads inconsistently?

Often, yes. Many classic tach systems are affected by noise/spikes in the tach lead (commonly worse with HEI or aftermarket ignitions). This filter is designed to help reduce interference for steadier readings.

My tach acted up after an HEI or ignition upgrade—why?

Higher-energy ignitions can introduce more switching noise into the tach signal wire. Some factory-style tachometers and older tach circuits are sensitive to that interference. A signal filter can help condition the tach signal.

Will this work with MSD, Holley, or other aftermarket ignitions?

It is commonly used with HEI and many aftermarket systems to help clean up the tach signal. If your ignition box has multiple tach outputs, use the recommended tach output and install the filter in-line as instructed.

If the tach still isn’t reading correctly, what should I check?

• Verify the tach is connected to the correct tach output/terminal (or tach adapter, if required).
• Inspect grounds and connectors for corrosion, looseness, or damaged wiring.
• Confirm the tach matches the engine/cylinder configuration.
• Route the tach lead away from high-voltage ignition wiring to reduce induced noise.

Is this “universal” for every tachometer?

We avoid “fits all” claims because tach systems vary. This filter is commonly used on many GM-era, factory-style tachometer applications and is intended to help reduce ignition noise that affects signal stability.

Learn more: How tachometer filters work, and will it work for my application