Pontiac had a special series of V8 engines from 1954 through the 1970s. It was neither a small-block nor a big-block really, but would be best classified in the latter group. Displacements ranged from 326 to 455 in³ (5.3 to 7.5 L).

Pontiac engines, as in the picture, were generally painted in light blue.

Pontiac/GMC V8

From 1955 through 1958, Pontiac shared a V8 design with GMC trucks. This family was a conventional OHV/pushrod design.

287

The 287 in³ (4.7 L) engine was only used in Pontiac cars.

288

The 288 in³ (4.7 L) engine was only used in GMC trucks.

316

The 316 in³ (5.2 L) engine was used in both Pontiac and GMC vehicles.

336

The 336 in³ (5.5 L) engine was only used in GMC trucks.

347

The 347 in³ (5.7 L) engine was used in both Pontiac and GMC vehicles.

370

The 370 in³ (6.1 L) engine was only used in Pontiac cars.

Aluminum V8

Pontiac shared the Oldsmobile/Buick aluminum V8 for a short time before replacing it with their own 326.

215

The Oldsmobile/Buick 215 V8 used by the 1961 and 1962 Pontiac Tempest is documented further under Buick V8 engine page.

Pontiac "Big-Block"

Pontiac's "big-block" engine family ranged from 370 in³ (6.4 L) to 455 in³ (7.5 L). It was produced from 1959 through 1979.

The 421 in³ (6.9 L) and higher engines had a larger 3.25 in (83 mm) journal.

195

The 1961-1963 194.5 in³ (3188 cc) member of the Pontiac engine family was not a V8 at all but rather a straight-4. According to Road & Track, the engine was simply half of a Pontiac V8, sharing the big engine's 3.75 in stroke with a new 4.06 in bore. This was perhaps possible by sharing the 4.057 in pistons from the Chevrolet 350 in³ small-block. The 195 produced 110 hp (gross) at 3800 RPM and 190 ft.lbf at 2000 RPM.

389

The 389 in³ (6.4 L) 389 was the original GTO engine. It produced 325 hp (242 kW) or, with Tri-Power (3 2-barrel carburetors), 348 hp (260 kW).

400

The 400 in³ (6.6 L) 400 V8 was a bored-out Pontiac 350 with 4.121 in bore and 3.75 in stroke. It was used in the 1967-1971 GTO.

In 1974, Pontiac started offering smaller engines in the Trans Am. The 400 engine was the only other option to the 455 in the 1974, 1975, and 1976 models. In 1977, Pontiac offered the 400 as the "high performance" option with the Olds 403 as the standard engine for the Trans Am. [1] The 400/403 options were available until 1980 when, because of the still ever increasing emissions restrictions, Pontiac dropped all of its big cubic inch motors.

421

421 in³ (6.9 L) 421.

428

428 in³ (7.0 L) 428.

455

The 1971 455 in³ (7.5 L) 455 was a low-revving torque machine, replacing the 428. It produced 500 lb.ft (678 Nm) of torque and just 360 hp (268 kW). In 1973, a reinforced Super-Duty version was made available. The Pontiac 455 V8 used a 4.152 in bore and 4.21 in stroke.

The 455 motor first made its appearance in 1971 as the 455-HO. In 1972, the 455 was altered internally and rebadged the 455-SD. [2] Pontiac offered the 455 for a few more years, but tightening restrictions on vehicle emissions guaranteed its demise. The 1976 Trans Am was the last of the "Big Cube Birds" with only 7,100 units made with the 455 engine. [3]

Pontiac "326"

A smaller engine was needed in the mid-1960s, so Pontiac developed a one-off 326 in³ (5.3 L) V8.

326

Pontiac produced a special 326 in³ (5.3 L) in 1963's Tempest Le Mans. Output was 264 hp (197 kW). This engine remained in production from 1963 through 1967.

For 1967, this was known as the 326 in 2-barrel carburetor form, and was option L30 for the Pontiac Firebird. A higher-output version, called the L76, had a 4-barrel carb, dual exhausts, and higher compression, and was good for 285 hp (213 kW).

Pontiac "Small-Block"

Pontiac's own "small-block" V8 was available in sizes similar to the Chevrolet Small-Block engine but was of a different design. It was produced from 1968 through 1980.

301

The 301 in³ (4.9 L) 301 was produced from 1977 onward. It was a "thin-wall" design, and a turbocharged variant was also produced.

1980 saw the biggest engine changes for the Firebird. The 301, offered in 1979 as an option, was now the standard engine. A turbocharged version of the 301 and the Chevy 305 were also offered. [4]

350

The Pontiac 350 in³ (5.7 L) V8 used a 3.876 in bore and 3.75 in stroke.

403

Despite the similar displacement to the venerable Pontiac 400 used from 1967 to 1979, the 403 engine installed in late '70's Trans Ams was not produced by Pontiac, but rather an Oldsmobile. The Olds 403 shares no parts with the traditional Pontiac V8.

265

Another thin-wall engine was the 1977+ 265 in³ (4.3 L) 265.

See also

• Pontiac Straight-8 engine
• Pontiac Straight-6 engine

From the 1950s through the 1970s, each GM division had its own V8 engine family. Many were shared among other divisions, but each design is most-closely associated with its own division:

• Buick V8 engine
• Cadillac V8 engine
• Chevrolet Small-Block engine
• Chevrolet Big-Block engine
• Oldsmobile V8 engine

GM later standardized on the later generations of the Chevrolet design:

• GM LT engine - Generation II small-block
• GM LS engine - Generation III/IV small-block
• List of GM engines