Chevy Corvette V8 HEI Distributor with Mechanical Tach Drive

• Includes mechanical tach drive — required for cable-driven Corvette and GM tachometer applications

• Fits SBC 262–400 and standard deck BBC 396–454 — tall deck BBC not compatible

• 65,000-Volt internal HEI coil — single 12V wire, no external coil or box needed

• Mechanical and vacuum advance — vacuum adjustment tool and instructions included

The TSP HEI Distributor with Mechanical Tach Drive is the correct ignition upgrade for Chevrolet small block and standard-deck big block V8 applications that use a cable-driven mechanical tachometer. Functionally identical to the standard TSP Chevy HEI distributor in ignition performance, this unit adds a mechanical tachometer drive provision on the distributor housing — the cable connection required to operate factory-style cable-driven tachometers found in the Corvette C2 (1963–1967), Corvette C3 (1968–1982), and other GM applications with mechanical tach setups.

If your vehicle does not use a cable-driven mechanical tachometer, the standard TSP Chevy HEI distributor (without tach drive) is the correct unit. Not all Camaro, Chevelle, Nova, or Impala applications used mechanical tachometers — verify your vehicle's tachometer type before ordering. The mechanical tach drive provision on this distributor is non-functional on vehicles with electronic tachometers and adds no benefit.

Engine fitment covers the full Chevrolet small block Gen. I family — 262, 283, 302, 305, 327, 350, and 400 CID — and the standard-deck Chevrolet big block family — 396, 402, 427, and 454 CID. This distributor is not compatible with tall-deck big block Chevy engines. Will not fit if a governor device is present in the distributor drive location.

The self-contained large-cap HEI design integrates the ignition coil, ignition module, cap, and rotor into a single unit, connecting to a single 12-volt source with no external coil, ignition box, or condenser required. The 65,000-volt internal HEI coil delivers substantially stronger spark than a factory points-style distributor, supporting easier cold starts, cleaner idle quality, and more consistent ignition performance. Both mechanical and vacuum advance are included, with a vacuum advance adjustment tool shipped with the distributor.

What Is a Mechanical Tach Drive and Do You Need One?
A mechanical tachometer drive is a provision on the distributor housing that accepts a tachometer cable — the same type of cable that connects a speedometer to a transmission output shaft, but for RPM measurement instead of vehicle speed. Cable-driven mechanical tachometers were used in many performance-era GM vehicles, most notably the Corvette C2 (1963–1967) and Corvette C3 (1968–1982) instrument clusters. Without a mechanical tach drive on the distributor, a cable-driven tachometer has no signal source and will not operate.

If your vehicle uses an electronic tachometer that picks up signal from the ignition system electronically, you do not need this unit — the standard TSP Chevy HEI distributor without tach drive is the correct choice and is less expensive. Only order this tach drive version if your vehicle's tachometer uses a physical cable connection to the distributor.

Performance Benefit
The 65,000-volt internal HEI coil delivers substantially stronger spark than a factory points-style or worn stock HEI distributor across the full RPM range. The magnetic pickup trigger holds timing accurately without the wear and drift that accumulates in points-based systems. Both mechanical and vacuum advance are included, and the vacuum advance adjustment tool allows the vacuum advance curve to be tuned for your specific engine combination and driving conditions.

What is a mechanical tach drive and why does the Corvette need one?
A mechanical tach drive is a provision on the distributor housing that accepts a tachometer cable—a physical cable that transmits RPM information to a cable-driven tachometer gauge. The Corvette C2 (1963–1967) and C3 (1968–1982) instrument clusters used cable-driven mechanical tachometers as standard equipment. Without a mechanical tach drive on the distributor, these cable-driven tachometers have no signal source and will not function. If your Corvette or other GM vehicle has a cable-driven mechanical tachometer, this is the correct distributor. If your vehicle uses an electronic tachometer, the standard TSP Chevy HEI distributor without a tach drive is the correct choice.

How do I know if my vehicle uses a mechanical tach drive distributor?
Look at the back of your tachometer gauge or at the existing distributor. If there is a cable running from the distributor to the instrument cluster (similar to a speedometer cable), your vehicle uses a mechanical tach drive. If the tachometer receives its signal electronically from the ignition system with a wire rather than a cable, you do not need this unit. When in doubt, inspect the existing distributor—if it has a cable fitting on the housing, it is a mechanical tach drive unit.

What engines does this distributor fit?
This distributor fits the Chevrolet small block Gen. I V8—262, 283, 302, 305, 327, 350, and 400 CID—and the standard-deck Chevrolet big block V8—396, 402, 427, and 454 CID—in carbureted applications. It is not compatible with tall-deck big block Chevy engines. It will not fit if a governor device is present in the distributor drive location.

What Corvette years does this distributor fit?
This distributor fits the Corvette C2 (1963–1967) with 327 or 427 V8 engines and the Corvette C3 (1968–1982) with 350, 396, 427, or 454 V8 engines, all of which used cable-driven mechanical tachometers as standard equipment. Confirm your specific engine is within the confirmed small block Chevy (SBC) or standard-deck big block Chevy (BBC) fitment range before ordering.

What is the difference between this distributor and the standard TSP Chevy HEI (without tach drive)?
The only functional difference is the mechanical tachometer drive provision on this distributor's housing. All other specifications are identical—same HEI design, same 65,000-volt coil, same magnetic pickup, same advance system, and same installation. If your vehicle does not use a cable-driven mechanical tachometer, the standard TSP Chevy HEI distributor without a tach drive is the correct and less expensive choice. The mechanical tach drive provision on this unit is non-functional on electronic tachometer applications.

Will this fit a tall deck big block Chevy?
No. This distributor fits standard-deck big block Chevy engines (396, 402, 427, and 454 standard deck) only. It is not compatible with tall-deck big block Chevy engines. Verify your BBC block deck height before ordering.

Does this distributor include an ignition coil?
Yes. The ignition coil is built into the distributor cap as part of the HEI design. No external coil is required. The only external connection needed is a single 12-volt hot wire.

Do I need an external ignition box or control module?
No. The ignition control module is integrated internally within the distributor. No external ignition box, CDI unit, points, or condenser is required.

What is the coil output voltage?
This distributor produces 65,000 volts of coil output, significantly higher than a factory points-style distributor, delivering a stronger, more consistent spark for improved cold starts, idle stability, and throttle response.

What type of distributor gear is included?
This distributor includes a steel distributor gear. Steel gears are most compatible with cast iron hydraulic or solid flat tappet camshafts. For roller camshaft applications, consult your camshaft manufacturer for the recommended gear material, as a mismatched gear and cam combination will cause accelerated wear on both components.

Do I need to set ignition timing after installation?
Yes. Base ignition timing must be set with a timing light after installation. For most carbureted SBC applications, a starting point of 6–12 degrees BTDC at idle is a common reference, though the optimal setting will vary based on your compression ratio, camshaft profile, and carburetor tune. Consult your engine builder or tuner for a specific recommendation.

Is this distributor compatible with a 6-volt system or generator?
No. This distributor requires a 12-volt electrical system with a charging alternator. It is not compatible with 6-volt systems, generators, or ballast resistors.