Buick Even Fire V6 HEI Distributor

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.