1967 Buick Gran Sport Convertible: A Blend of Style & Muscle

The 1967 model year marked a significant evolution for the Buick Gran Sport line. With a potent new engine replacing the venerable “nailhead,” a distinct identity separate from the Skylark series, and refined styling, the Gran Sport asserted itself more forcefully in the competitive muscle car arena. Among the offerings, the 1967 Buick Gran Sport Convertible stood out as the premium choice, combining open-air motoring with serious performance credentials. This year solidified the Gran Sport’s path toward becoming a true performance icon.

A New Heart: The End of the “Nailhead” Era

Under the hood, the biggest change for the 1967 Gran Sport was the introduction of a new 400-cubic-inch V-8 engine. This powerplant signaled the end of the previous “nailhead” engine design. The new engine featured significant improvements aimed at better breathing and efficiency. Key upgrades included larger manifold branches, bigger valves (18% larger intake, 56% larger exhaust compared to 1966), and improved exhaust headers to minimize gas flow restriction.

Further engineering refinements included redesigned water jackets in the cylinder heads that circulated coolant around the spark plug holes for better temperature control. Conical spark plug seats were also adopted, eliminating the need for traditional plug washers.

Larry Gustin and Terry Dunham, in The Buick: A Complete History, detailed the rationale behind the engine change. The previous design, with its vertical valves and pent-roof combustion chamber, limited valve and port sizes. The new engine utilized a “slanted saucer” domed chamber designed by engineer Joseph Turlay. This allowed for conventional rocker arm and pushrod placement and a 15-degree valve angle, improving breathing flexibility. Additionally, this domed chamber had less surface area relative to displacement volume compared to a conventional wedge design. While not reducing octane requirements, it resulted in higher efficiency—boosting power and fuel economy—and reduced hydrocarbon emissions.

Forging Its Own Identity: Beyond the Skylark

For 1967, the Gran Sport officially shed its previous designation as a Skylark sub-model. As Popular Mechanics noted, Buick likely felt the Gran Sport needed a more distinct, masculine identity, “divorcing” the GS-400 from the Skylark series. This move catered to buyers seeking a dedicated performance machine.

Styling was subtly updated to reflect this independence. The dummy hood scoops were reshaped. Instead of the fender skirts available on Skylarks, the GS featured open rear wheel housings, proudly displaying its standard F70 x 14 wide-oval tires, available with red or white stripes. The grille received a bolder look with a thicker horizontal bar intersected by a prominent vertical spine, and the taillights were slightly enlarged. Cars optioned with front disc brakes also received specific wheels, hubcaps, and beauty rings.

Enhanced Performance and Handling

Buick’s braking systems, already well-regarded, received further enhancements for 1967. Gustin and Dunham noted improvements across the lineup, including optional front power disc brakes for most models. The GS-400 benefited from aluminum front brake drums (also used on the Sportwagon). Larger Buick models received bigger power boosters, improved linings, and drums with double the cooling fins.

Red 1967 Buick Gran Sport convertible parked outdoors, showcasing its premium GS-400 styling.

These upgrades translated to tangible performance gains. Car Life magazine, comparing their 1967 GS-400 test car to a 1965 Gran Sport, recorded faster acceleration (0-60 mph in 6.6 seconds) and quarter-mile times (14.7 seconds). Crucially, the 1967 model equipped with front disc brakes demonstrated significantly improved deceleration from 80 mph with virtually no fade, addressing criticisms leveled at the all-drum brakes of earlier models.

Interior view of a 1967 Buick GS-400 convertible featuring automatic transmission and full-length console.

Introducing the GS-340: Accessible Muscle

Recognizing that the GS-400’s price point might be prohibitive for some buyers, Buick introduced the GS-340 for 1967. Advertised as offering its “own brand of excitement” at a lower cost, the GS-340 provided a stepping stone into Gran Sport ownership. Available only as a two-door hardtop, it started at $2,845, slightly less than the GS-400 models.

Power came from a 340-cid V-8 engine producing 260 horsepower and 365 lb-ft of torque, breathing through a four-barrel carburetor and featuring a 10.25:1 compression ratio. Buyers could opt for a four-speed manual transmission or an automatic; pairing the automatic with bucket seats allowed for the addition of a full-length console. To handle the power, the GS-340 received specific front and rear shock absorbers, special springs, a large-diameter stabilizer bar, and rode on 7.75 x 14 rayon tires mounted on rally-style wheels. Visually, the GS-340 was distinguished by its limited color palette (white or platinum mist silver), accented with bold red rally stripes, matching hood scoops, and a red lower-deck molding.

White 1967 Buick GS-340 hardtop identified by its distinctive red rally stripes and hood scoops.

1967 Production Snapshot

The introduction of the GS-340 helped boost total Gran Sport production to 17,505 units for the model year. The new GS-340 accounted for 3,692 of these sales. The GS-400 hardtop remained the most popular variant, with 10,659 examples produced. The 1967 Buick Gran Sport Convertible, positioned as the premium GS-400 offering, started at $3,167. While convertible production numbers were lower overall compared to the hardtop, the rarest configuration was the GS-400 convertible equipped with a three-speed manual transmission – only nine such cars were ever built, highlighting its exclusivity. The most common convertible was the GS-400 automatic.

Conclusion

The 1967 Buick Gran Sport represented a crucial step in Buick’s muscle car journey. With its powerful new 400-cid engine, a clearer identity separate from the Skylark, improved handling, and the introduction of the accessible GS-340, Buick demonstrated its commitment to performance. The 1967 Buick Gran Sport Convertible, in particular, embodied the blend of open-air style, comfort, and V8 power that defined American muscle cars of the era. While later “Stage” versions would achieve legendary dragstrip status, the 1967 models laid the essential groundwork, creating desirable classics known for delivering performance with signature Buick style and comfort.