Buick Small-Block

In 1961 Buick unveiled an entirely new small V8 engine with aluminum cylinder heads and cylinder block. Lightweight and powerful, the aluminum V8 also spawned a turbocharged version, (only in the 1962-63 Oldsmobile Cutlass version), the first ever offered in a passenger car. It became the basis of a highly successful cast iron V6 engine, the Fireball. The all-aluminum engine was dropped after the 1963 model year, but was replaced with a very similar cast-iron engine.


215

GM experimented with aluminum engines starting in the early 1950s, and work on a production unit commenced in 1956. Originally intended for 180 in³ (2.9 L) displacement, Buick was designated by GM as the engine design leader, and decided to begin with a larger, 215 in³ (3.5 L) size, which was deemed ideal for the new "senior compact cars" introduced for the 1961 model year. This group of cars was commonly called the BOP group or A-bodies.

The 215 had a 4.24 in (107.7 mm) bore spacing, a bore of 3.5 in (88.9 mm), and a stroke of 2.8 in (71.1 mm), for an actual displacement of 3533 cc. The engine was the lightest mass-production V8 in the world, with a dry weight of only 318 lb (144 kg). It was standard equipment in the 1961 Buick Special.

Oldsmobile and Pontiac also used the all-aluminum 215 on its mid-sized cars, the Oldsmobile F-85 and Pontiac Tempest. However the Oldsmobile version of this engine, although sharing the same basic architecture, had cylinder heads designed by Oldsmobile engineers, and was produced on a separate assembly line. Among the differences between the Oldsmobile and Buick versions, it was somewhat heavier, at 350 lb (159 kg). The design differences were in the cylinder heads: Buick used a 5-bolt pattern around each cylinder where Oldsmobile went to a 6-bolt pattern. The 6th bolt was added to the intake manifold side of the head, one extra bolt for each cylinder. This was supposed to alleviate the head-warping problems that came about on the higher compression ratio versions. Later Rover versions of the aluminum block and subsequent Buick iron small blocks (300, 340 and 350) went to a 4 bolt per cylinder pattern.

At introduction, Buick's 215 was rated 150 hp (112 kW) at 4400 rpm. This was raised soon after introduction to 155 hp (116 kW) at 4600 rpm. 220 ft·lbf (298 N·m) of torque was produced at 2400 rpm with a Rochester 2GC two-barrel carburetor and 8.8:1 compression ratio. A mid-year introduction was the Buick Special Skylark version, which had 10.25:1 compression and a four-barrel carburetor, raising output to 185 hp (138 kW) at 4800 rpm and 230 ft·lbf (312 N·m) at 2800 rpm.

For 1962, the four-barrel engine increased compression ratio to 11.0:1, raising it to 190 hp (142 kW) at 4800 rpm and 235 ft·lbf (319 N·m) at 3000 rpm. The two-barrel engine was unchanged. For 1963 the four-barrel was bumped to an even 200 hp (149 kW) at 5000 rpm and 240 ft·lbf (325 N·m) at 3200 rpm, a respectable 0.93 hp/in³ (56.6 hp/liter).

Unfortunately, the great expense of the aluminum engine led to its cancellation after the 1963 model year. The engine had an abnormally high scrap ratio due to hidden block-casting porosity problems, which caused serious oil leaks. Another problem was clogged radiators from antifreeze mixtures incompatible with aluminum. It was said that one of the major problems was because they had to make extensive use of air gaging to check for casting leaks during the manufacturing process, and not being able to detect leaks on blocks that were as much as 95% complete. This raised the cost of complete engines to more than that of a comparable all cast-iron engine. Casting sealing technology was not advanced enough at that time to prevent the high scrap rates.

The Buick 215's very high power to weight ratio made it immediately interesting for automotive and marine racing. Mickey Thompson entered a stock-block Buick 215-powered car in the 1962 Indianapolis_500. From 1946 to 1962 there hadn't been a single stock-block car in this famous race. In 1962 the Buick 215 was the only non-Offenhauser powered entry in the field of 33 cars. Rookie driver Dan_Gurney qualified eighth and raced well for 92 laps before retiring with transmission problems.

Surplus engine blocks of the Oldsmobile (6 bolt per cylinder) version of this engine formed the basis of the Formula One Repco V8 used by Brabham to win the 1966 and 1967 Formula One championship. No other American stock-block engine has won a Formula One championship.

Buick 215s have been engine swapped into countless sports cars including especially Chevrolet Vegas and MG sports cars. The engine remains well supported by enthusiast clubs, specialist parts suppliers, and by shops that specialize in these conversions.

The Buick 215 was used in a small sports car known as the Apollo from 1962 to 1963, and also in the Asardo 3500 GM-S show car.

Although dropped by GM in 1963, in January 1965 the tooling for the aluminum engine was sold to Britain's Rover Group to become the Rover V8 engine, which would remain in use for more than 35 years. GM tried to buy it back later on, but Rover declined, instead offering to sell engines back to GM. GM refused this offer.


300

In 1964 Buick replaced the 215 with an iron-block engine of very similar architecture. The new engine had a bore of 3.75 in (95.5 mm) and a stroke of 3.40 in (86.4 mm) for a displacement of 300.4 cu. in. (4.9 L). It retained the aluminum cylinder heads, intake manifold, and accessories of the 215 for a dry weight of 405 lb (184 kg). The 300 was offered in two-barrel form, with 9.0:1 compression, making 210 hp @ 4600 rpm and 310 ft·lbf @ 2400 rpm, and four-barrel form, with 11.0:1 compression, making 250 hp @ 4800 rpm and 335 ft·lbf @ 3000 rpm.

For 1965 the 300 switched to a cast-iron heads, raising dry weight to 467 lb (212 kg), still quite light for a V8 engine of its era. The four-barrel option was cancelled for 1966, and the 300 was replaced entirely by the 350 in 1968.

The Apollo sports car, also known as the Vetta Ventura, used this engine.


340

The 340 in³ (5.6 L) 340 was a stroked (to 3.85 in/97.8 mm) version of the 300. It had a two-barrel or four-barrel carburetor, the two barrel with 220 hp, and the four barrel with 11.0:1 compression, rated at 260 hp @ 4200 rpm and 365 ft·lbf @ 2800 rpm. It replaced the four-barrel 300 for 1966. It was produced only in 1966 and 1967, with the new Buick 350 taking its place after that.


350

Buick adopted the popular 350 in³ (5.7 L) size with their final family of V8s. Although sharing the displacement of the Chevrolet Small-Block engine family, the Buicks were substantially different.

The Buick 350 V8 had a 3.80 in bore (like the 231) and retained the 3.85 in stroke of the 340. It was introduced in 1968 and produced through 1980.

The major differences of the Buick 350 when compared to other GM V8's are, deep skirt block construction, higher nickel-content cast iron, external oil pump, under square bore sizing, 3.0" crank main journals, and 6.5" connecting rods. It is an extremely rugged and durable engine, and some of the design characteristics of the Buick 350 are found in modern GM engines such as the 231 V6, and Series I, II, and III 3800 V6's.

Of all the GM 350-inch engines, the Buick 350 has the longest stroke, which lends to making significantly more torque than any of the others. It also made the Buick 350 significantly wider - essentially the same width as the Buick big-blocks, which have the shortest stroke of the GM big-blocks. In fact, at a glance the buick 350 is commonly mistaken for the 455 engine due to the oversized intake manifold atop the engine. The Buick 350 also shares an integrated Aluminum timing cover as do most of the Buick small & big blocks that incorporates the oil pump mechanisms as well. Leaving the oil filter exposed to oncoming air for added cooling.

The Buick 350 was used in the Jeep Gladiator and Wagoneer from 1968 to 1971.