Buick Even Fire V6 HEI Distributor

• Fits Buick 90° Even-Fire 231 V6 — 1977–1987 carbureted GM applications

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

• Fits Buick, Chevrolet, Oldsmobile, and Pontiac platforms — A, G, F, and B-body

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

The TSP HEI Distributor for the Buick 90° even-fire V6 is a self-contained large-cap HEI ignition upgrade for the 3.8L (231 CID) even-fire V6 used across multiple GM vehicle lines from 1977 through 1987. The integrated HEI design combines 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 even-fire Buick 231 V6 was one of GM's most widely shared powerplants of the late 1970s and early 1980s, appearing in Buick, Chevrolet, Oldsmobile, and Pontiac vehicles across the A-body, G-body, F-body, and B-body platforms. This HEI distributor covers carbureted applications across all of these platforms in a single direct-fit unit — making it one of the most broadly applicable V6 distributor upgrades in the GM rear-wheel-drive era.

The 65,000-volt internal HEI coil delivers substantially stronger spark than a factory points-style or worn stock HEI distributor, supporting easier cold starts, cleaner idle quality, and more consistent ignition performance across the RPM range. A magnetic pickup trigger requires no routine maintenance and holds timing more accurately over time than a contacts-based system. Both mechanical and vacuum advance are included, with a vacuum advance adjustment tool shipped with the distributor.

Understanding the Even-Fire 231 and Why the Upgrade Matters
GM transitioned the Buick 90° V6 from odd-fire to even-fire architecture beginning in the 1977 model year. Where the odd-fire 231 used a 90° crankshaft that created uneven firing intervals, the even-fire 231 uses a reworked crankshaft with equal 120° firing intervals — a smoother, more refined design that became the foundation for the Buick V6 family through the 1980s. The even-fire 231 appeared in Buick, Chevrolet, Oldsmobile, and Pontiac vehicles across multiple rear-wheel-drive platforms from 1977 through 1987 as a widely shared GM powertrain. These two distributor designs — odd-fire and even-fire — are not interchangeable. Verifying your engine architecture before ordering is essential, particularly for 1977 model year vehicles where both types were produced.

Performance Benefit
The 65,000-volt internal HEI coil fires spark plugs more consistently than a stock or aging factory distributor across the full RPM range. Stronger, more consistent spark translates to easier cold starts, cleaner idle quality, and improved throttle response — particularly on vehicles where the factory ignition system has aged, drifted, or been poorly maintained. 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 engines and vehicles does this distributor fit?
This distributor fits the Buick 90° even-fire 3.8L (231 CID) V6 in carbureted applications from 1977 through 1987. The even-fire 231 was shared across multiple GM divisions and platforms, including Buick Regal, Century, LeSabre, Skylark, and Electra; Chevrolet Camaro, Malibu, Monte Carlo, and El Camino; Oldsmobile Cutlass, Delta 88, and Omega; and Pontiac Firebird, Grand Prix, and LeMans in applicable years and configurations. This distributor is not compatible with the earlier odd-fire Buick V6, the later Buick 3800 V6, or any front-wheel-drive application.

What is the difference between the even-fire and odd-fire Buick 231 V6, and how do I know which one I have?
The odd-fire Buick 231 uses a 90° crankshaft that creates uneven firing intervals—cylinders fire at alternating 90° and 150° intervals. The even-fire 231 uses a reworked crankshaft with equal 120° firing intervals, producing smoother power delivery. These two designs require different distributors and are not interchangeable. Most 1975–1976 vehicles with the Buick 231 are odd-fire. Most 1978 and later vehicles are even-fire. For 1977 vehicles, both were produced during the model year, so confirm your engine type by checking the engine casting number before ordering.

Does this distributor fit the Buick 3800 V6?
No. This distributor is not compatible with the Buick 3800 V6 in any series or configuration. The 3800 uses a different ignition system architecture and is not supported.

Does this distributor fit a turbocharged Buick Regal, Grand National, or T-Type?
No. This distributor is designed for carbureted even-fire 231 V6 applications only. The turbocharged Regal, Grand National, and T-Type use a different ignition system specific to their forced-induction setup and are not compatible with this distributor.

Will this fit my Chevrolet Camaro or Pontiac Firebird?
Yes, for 1977–1981 Firebird and 1980–1981 Camaro models equipped with the carbureted even-fire Buick 231 V6. Confirm your vehicle has the 231 even-fire V6 specifically—not all Camaro and Firebird models in these years used this engine, and later models used different V6 or V8 engines that are not compatible with this distributor.

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 on this distributor?
This distributor produces 65,000 volts of coil output—significantly higher than a stock or worn factory HEI distributor—providing a stronger, more consistent spark for improved cold starts, idle stability, and throttle response.

Does this distributor fit front-wheel-drive GM vehicles?
No. This distributor is designed for rear-wheel-drive carbureted applications using the even-fire 231 V6 only. It is not compatible with front-wheel-drive GM vehicles.

What type of advance does this distributor use?
This distributor uses both mechanical (centrifugal) advance and vacuum advance. Mechanical advance increases ignition timing as engine RPM rises. Vacuum advance adds additional timing under light throttle and cruise conditions. A vacuum advance adjustment tool is included to allow tuning of the vacuum advance curve for your application.

What type of distributor gear is included?
This distributor includes a steel distributor gear. Steel gears are compatible with cast iron camshafts and most aftermarket steel camshafts. If your engine has a roller camshaft with a bronze or softer alloy cam gear, verify gear compatibility before installation, as mismatched gear and cam materials will cause accelerated wear on both components.

Do I need to set ignition timing after installing this distributor?
Yes. Base ignition timing must be set with a timing light after installation. For most carbureted even-fire Buick 231 applications, a starting point of 12–15 degrees BTDC at idle is a common reference, though the optimal setting will vary based on your compression ratio, camshaft profile, and carburetor tune.

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.

Does this distributor have a mechanical tachometer drive or tachometer output?
No. This distributor does not include a mechanical tachometer drive or a dedicated tachometer output signal. Vehicles requiring a tachometer signal will need an electronic tachometer with a compatible signal adapter.