A Modern V8 from a Straight 8 Company

The Generation 1 V-8 “Nailhead” was a radical departure from Buick’s history of overhead valve straight-8 cylinder engines produced beginning in 1931. Thus, the Nailhead engine was an engineering breakthrough when it was delivered in 1953, in that it was narrow and relatively light compared to the Olds, Caddy, Lincoln – and even the small Ford 234 V-8.

It had a very short stroke and for the time, a huge bore, keeping the deck height way under those of its competitors. At introduction, the valve sizes were not that much smaller than the others in this engine size, and no one knew how restrictive this would become later on. It was considerably lighter and much more compact than the straight 8 it replaced, and developed almost 1.5 times the power for the same displacement.

Thus the Nailhead became the bread and butter engine for Buick from 1953 until 1967, when it was replaced by the “Gen 3” big block V8.

Series 1 Nailhead Engines

Buick’s first series of Nalihead V8s were used from 1953 through 1956. Like all Buick engines, It was an OHV/pushrod engine. The engine became known as the “Nailhead” because of the unusual vertical position of its small-sized valves which were tagged by the press as “nail heads”.

The Nailhead-V8 family employed a camshaft with higher lift and longer duration to offset the smaller-sized valves and arguably restrictive intake and exhaust-port areas. The valve size was small at 1.75″ for the intakes and 1.25″ for the exhaust.

The nature of this design was to take the advantages of the pent-roof combustion chamber design of four-valve racing cylinder heads, where intake and exhaust valves were on separate sides of the combustion chamber (many time with two valves per intake and exhuast), but flame travel was consistant, due to the central placement of the spark plug and the “pent roof” chamber design.

Where the Nailhead differed from race engines was that one side of the set of valves were removed from what would commonly be the exhaust side – and to orient both the intake and exhaust on the more common intake side and twist the exhaust port to exit on the opposite side of the head. This made for both smaller valves and a rather restrictive exhaust runner, but it did�result in a compact head design, with the motor being one of the most compact V8s for its time even at the then quite large size of 322 cubic inches.

This compact head size�did reduce the future horsepower potential of the engine, though at the time of release this was not an issue. The small-size valves and intake runners did howver make for engines with a lot of torque, with most Buicks exceeding one foot-pound per cubic inch, which was exceptional for the day and resulted in great pulling power on the street.

This first series of engines were�delineated by oval cylinder exhaust ports, a lower deck height, and a different camshaft bearing size. As a result of this, few parts in the early series engines exchange with later versions, hence the Generation 1 desgination. First year engines also used a different design piston and combustion chamber and also will not exchange with 1955 and 56 engines, making the first year even more unique.

The 264 cubic in model was designed for the Buick “Special” series cars, and was a direct replacement for the 263 cubic inch straight-8 used in Buick’s large cars, which surprisingly was available in the Special in 1953. The 264 was introduced a year after the 322 and only produced in 1954 and 1955. In its best configuration, it developed 188 hp @ 4800 rpm and 256 ft. lbs. of torque @ 2400 rpm.

The larger 322 cubic inch V8 was used by Buick from 1953 through 1956, primarily in ‘senior’ (read larger wheelbase) series cars, the Super, Century, and Roadmaster. The Super received a 2-barrel carburetor and lower compression, while the Century and Roadmaster received a 4-barrel and higher compression. In 1956, the 264 was dropped and the Special Series received the former Super’s 322 low compression 2 bbl. engine, while all other Series utilized the 4-barrel unit. Power in the senior series cars resulted from higher compression, a 4-barrel and optional dual exhausts. The 322 was a very capable performer for its time, with its best power figures of 255 hp @ 4400 rpm and 341 ft. lbs of torque @ 3200 rpm. Only Cadillac exceeded the Buick’s power output and that may have been overstated.

Series 2 Engines

The second generation Nailhead was produced from 1957 through 1966 and utilized the same cylinder head design features that were used from its inception until it was replaced by the more modern Gen 3 V8. Many improvements were introduced. Buick’s Generation 2 series of this V8 was also called a “Nailhead” as its valves and head were still configured in the same fashion. In this version, the ports were less restrictive and the valve sized enlarged as much as possible within the potential “valve span” across the cylinder bore centers, with the maximum intake valve size increased to 1.85″ and the exhaust valve to 1.50″. The camshaft duration was even more radical and the substitution of 1.6:1 ratio of rocker arms for the earlier version’s 1.5 ratio allowed even more valve lift, overcomeing the shortcomings in the small valve sizes.

The cylinder head improvements were improtant because Buick, like most of its competitors, continued to expand the durable V8 engine to larger displacements. For 1957 the engine now displaced 364 cubic inches, with a 4.125″ bore and a 3.40″stroke. The 364 was produced from 1957 through 1961. The 364 was detuned for the Special model, in standard form, though the 4-barrel dealer installed version was offered to those taking the smaller Buick racing. In 1957 the Century 364 high performance kit churned out 330 hp @ 4800 rpm, passing the fabled 300 HP mark. Maximum torque was an exceptional 400 ft. lbs @ 3200 rpm. With a three speed manual transmission, this car was no slouch!

The next member of the Generation 2 engine family was the 401 cubic inch version with an increased bore and stroke of 4.1875″ x 3.640″ over the 364. It was first offered in 1959 as the upscale engine and only available in the Invicta (former Century) and the Electra (former Roadmaster). The LeSabre, which replaced the Special made do with the 364.

The 401 was also found in the Riviera, when introduced in 1963, and the Wildcat performance car, when introduced in 1962. The 401 was later Buick’s muscle car powerplant when used in the company’s Skylark Gran Sport in 1965 and 1966. The 401 ran alonside the 364 from 1959 until 1962 when the 364 was dropped. The 401 then became the “junior” powerplant starting 1963 until it was replaced with the all new Gen 3 engine in 1967, being the longest running version displacement engine of all the Nailheads. Because of this, the 401 is still readily available in scrap yards for those looking to restore a vintage Buick.

The last iteration of the Nailhead was the 425 cubic inch model with its larger 4.3125″ bore, but same stroke as the 401. It was introduced in 1963 where it began as an option on the new Riviera. It was later available on the Wildcat and Electra models as well. Surprizingly, the 1964 and 1966 Riviera had the 425 engine as standard, but in 1965, the standard Riviera returned to the 401. Four barrel carburetion was standard on all 425 Nailheads, called the “Wildcat 465”. That “465” sticker on the air cleaner did not denote engine displacement as many thought, it denoted the torque rating, which BUick was very proud of, since it overshadowed almost every other V8 of the time.

The 425 was considered a true performance engine by Buick, and in 1964 it was possible to order a two 4 barrel carb intake, which was delivered in the trunk along with the the special 4-barrel carbs, to be installed by the dealer. In 1965 it was called “Super Wildcat” and it was standard as a factory installed option on the 1965 Riviera Gran Sport and the 1966 Wildcat “GS”. The 2-4s were still a “trunk option” for the rest of the Buick line for most of 1966. In May 1966, Buick offered this Super Wildcat 465 with dual 4BBL Carter AFB’s as a factory installed option on all 425 equipped Buicks, except for the Skylark GS where it was a dealer install on the 401. This is a very sought after option for restorers as it adds a bit of cache to the vehicle and is acceptable due to the�dealer installation�option.

Factory 425s with this 2 4 bbl option were coded “MZ” while the dealer installed dual four barrel setup was coded “MW”. Their were only 179 1966 Riviera GS cars built with the MZ coded factory dual four barrel setup, making it a very rare car. if you find one, let the Buick Club of America know – they are quite sought after collectibles.