The Ford flathead has been a prolific power plant of the classic hot rod or street rod for decades. But, for some, the flathead engine is just too common among vintage hot rods, and other engines are chosen for their own unique attributes. The Buick Nailhead is one of the engines.
The Buick Nailhead has long been a popular engine with vintage hot rodders. While Buick was not new to the OHV concept, the company preferred to put its eight cylinders in a row. In 1953 when Buick decided to put those eight cylinders in an opposing V configuration hot rodders took note.
A beautiful Nailhead engine powers this roadster, and it features great details such as center carb linkage, Weiand valve covers, and wire covers held in place with vintage Cal Custom wing nuts. Chrome headers and yes, a chrome frame are the makings of what could have been a mid-1960s cover car.
The Nailhead name speaks to the relatively small valves in these engines. While the small vertical valves may not make this engine a big breather in the high-RPM range, they produce torque—and lots of it! The vertical valve covers keep the motor narrow enough to fit between early frame rails with ease, but engine swaps are not without special problems.
Buick chose to mount the starter to the lower left side of the motor, which makes clearing steering boxes and routing exhaust a challenge. However, mounting the motor in most early Ford frames is fairly simple because motor mounts can easily be fabricated or purchased. The front mounts can be used to locate the engine atop the stock-style flathead biscuit-style motor mounts. The early motors all used a rather odd looking center sump oil pan, and for most hot rod applications, a later 1957–1961 rear sump pan has to be used along with the proper oil pumps.
Custom exhaust is almost a must on the left side of the motor, and while there are shorty headers available today, this style of header is too new for a period correct car. Having said that, if you’re building a period flavor car, these shorty headers solve a lot of fitment problems.
All Nailheads were not created equal. As a matter of fact, like many things over the years, they became wider. The early 322/264 motors are 81⁄4 inches between the heads, measuring from the front intake bolt hole on one head to the same hole on the opposite head. That same measurement grew to 85⁄8 on the 364-ci motors and the 401 engine takes that measurement to an even 9 inches. These changes can make buying vintage speed equipment a bit tricky.
The motor was a powerhouse from its introduction in 1953 with the 322-ci motor pumping out 188 hp. In 1954, a smaller 264-ci motor was produced for the Buick Special line, but the 322 would remain in production through 1956 when factory horsepower was rated at 255. The Nailhead family continued to grow to the famed 401-ci version introduced in the Invicta in 1959. The 364 remained in production until 1962 when the 401 became the standard engine for all full-size cars. By 1966 you could get 425 ci of Nailhead power in the Riviera with 340 hp on tap. The 1964–1966 motors had a modern TH400 automatic transmission bolted to them, and while the pre-1964 models don’t bolt up to the TH-400, a crankshaft adapter makes this swap a simple one.
If you can handle a little extra length and find some room on the left side for steering, the Buick engine in your hot rod is a great choice. These engines enjoy the one of the longest period appropriate time frames, as hot rodders were installing Nailhead motors from 1953 into the 1970s. Speed equipment and dress-up items are available, and one look at a Buick motor with a finned-aluminum valley cover, valve covers, and ignition wire covers is enough to convince any hot rodder to build it better with a Buick.
For many, the larger Nailhead engines are the most appealing, thus the 322s, 364s, and 425s are popular choices. If you opt for Nailhead power, make sure the exterior pieces retain that vintage hot rod look. Therefore, carefully select the alternator, water pump, valve covers, exhaust, and other equipment for your particular rod.