The 409 V8 may be a dead end in the Chevrolet high-performance story, but it’s a fascinating one, and more than worthy of a closer look. Here’s the lowdown on a nearly forgotten engine.
The 409 V8 is a missing link, if you will, in the history of Chevrolet horsepower. The engine might be best remembered today as the subject of an old Beach Boys song, oddly enough. Still, the 409 is an unusual and interesting engine. Let’s jump right in for a closer look.
The 409 story actually starts here, with the 348 cubic-inch W-Series V8 (above) introduced for 1958. Chevrolet product planners recognized that domestic passenger cars were rapidly growing in size and weight, topping two tons, and feared that the small but mighty 283 CID V8 would soon be insufficient. Experimental X and Y-Series engines, essentially scaled-up versions of the small-block V8, were tried before the Chevrolet engineering team, led by John Rausch, Howard H. Kehrl, and Donald H. McPherson, determined that an all-new engine was the preferred course.
The name for the W-Series V8 is easy to remember due to the distinctive valve cover shape, which resembles the letter W, sort of. Goals for the new V8 included low manufacturing cost and a compact footprint so it could fit in the same vehicle applications as the small-block. Mission accomplished, as the W-Series arrived only 2.70 inches wider and 1.78 inches longer than the existing V8. The initial 348 cubic-inch displacement was obtained with a bore of 4.125 in. and a stroke of 3.25 in. Bore spacing was 4.84 inches from center to center, identical to the Chevy Mark IV V8, better known as the big-block V8, that Chevrolet would introduce some years later (1965).
Of course, the trademark feature of the W-Series V8 was its distinctive combustion chamber design. In place of a conventional bowl-type chamber in the cylinder head. the block deck was milled at 74-degree angle (16 degrees from perpendicular) to form an oval, wedge-shaped chamber in the top of the cylinder itself. While unusual, this design was not quite unique. Ford Motor Co. also used this configuration on its MEL V8 engine family of 1958-1967, and it was found on some industrial engines in America and Europe.
According to SAE paper no. 590014 presented by General Motors in 1958, the design team was attracted to this design because it supported a variety of displacements and compression ratios with a minimum of tooling changes. The flat, chamberless cylinder head deck also provided generous squish and quench area, as shown in the illustration above. However, the setup did require a big, heavy piston with a tall compression crown, as we can also see. Compression ratio for the original 348 CID version of 1958 was set at 9.5:1, while the 409 CID V8 sported a CR of 11.25:1 when it launched in 1961.
Unlike the small-block Chevy and other V8s of the period, the W engine’s valves were not aligned in a single row but offset in two planes, which permitted larger valve diameters within the allotted bore spacing. (However, the valves were not splayed at multiple angles as in the later Mark IV big-block V8.) This layout also gives the W-Series its distinctive valve cover shape. On the original 348 V8, the valve diameters were a modest 1.94 inches and 1.65 inches for the intake and exhaust, respectively. On the 409 version, the valve sizes were eventually opened up to 2.20 and 1.72 inches.
Apart from the offset valves and flat, chamberless cylinder heads, the W-Series was a fairly conventional General Motors V8, with iron block and head castings and forged steel crankshaft and connecting rods. The lightweight, skirtless cylinder case and stamped, ball-mounted rocker arms (which enabled the staggered valve layout by eliminating the need for a rocker shaft) were familiar features borrowed from the small-block Chevy V8. The standard 348 CID V8 with single four-barrel carburetor was known as the Turbo-Thrust V8 in Chevy marketing lingo, while the performance version with three two-barrel carburetors (more on that fuel system here) was called the Super Turbo-Thrust V8, and it was ultimately rated at 350 hp in its final stage of factory development.
The big news for Chevy performance enthusiasts arrived midway through the 1961 model year with the introduction of the mighty 409 CID V8. The larger displacement was achieved with an increase in both bore and stroke to 4.312 inches by 3.50 inches, yielding exactly 408.89 cubic inches. The main and rod journal diameters and other features are the same as the 348, but the 409 crankshaft will not fit in a stock 348 block due to its larger counterweights. The 409 block is also thicker in the cylinder walls to support the .187-in. larger bore diameter, naturally.
While the 348 and the 409 are nearly identical in external appearance to the casual eye, there is one time-honored (but not totally foolproof) way to tell them apart. On the 348, the oil dipstick is on the left (driver) side of the engine, while on the 409 the dipstick is on the right (passenger) side.
As a mid-year, high-performance offering, the 1961 version of the 409 is relatively rare. Only 142 cars were built with the $484 option, which went into production in January of the model year. (For scale, Chevrolet produced more than 1.3 million vehicles that year.) Initially rated at 360 hp at 5,800 rpm and 409 lb-ft of torque at 3,600 rpm, the ’61 409 was equipped with a single Carter AFB four-barrel carburetor. However, a dual four-barrel aluminum intake manifold was soon made available over the parts counter at Chevrolet dealers for drag racing and other competition use.
The 409 enjoyed widespread availability for the first time—and truly got on the map—with the 409-horsepower version introduced for 1962. This was no doubt the version of the engine the Beach Boys were singing about in their 1962 hit song, 409. Sporting big-valve heads and a dual-quad intake manifold with a pair of Carter AFB D-Series carburetors, the engine quickly became top dog at the drag strips and drive-ins of the time, where it was known as the “Oh-nine Oh-nine” in hot rod slang. That is, 409 cubic inches, 409 horsepower, one horsepower per cubic inch.
More than 15,000 of these powerplants were produced by Chevrolet’s Tonawanda, New York engine plant, just north of Buffalo. These included around 9,000 units for the vehicle assembly lines, listed as Regular Production Option (RPO) 587 and priced at $376.65, and the rest for sale over the counter through the Chevy parts system.
Through its five-year production life (1961-1965) the 409 was offered not only in high-performance versions with high compression and multiple carburetion, but also in single-carb tune for regular highway use. Variously rated at 360 to 400 hp, these versions typically featured hydraulic valve lifters and unlike the 409/409, were available with an automatic transmission. The 409 also saw some truck use, notably in cabover-engine applications.
For serious drag racers, Chevrolet also offered a package of very special 409 pieces in 1962, including an improved two-piece intake manifold, revised cylinder heads, a trick camshaft, and lightweight aluminum body panels. No more than around 20 cars were assembled with these components, the experts say, but in the hands of top competitors including Dyno Don Nicholson and Dave Strickler, shown above, they were capable of quarter-mile times in the mid 12-second range at 112 mph. While the Z11 label is sometimes applied to these cars and components, Chevrolet did not release an official Z11 package until the following year.
The king of the 409 engine family technically isn’t a 409; it’s a 427. In 1963, shortly before the GM racing ban was enacted, Chevrolet built a short run of vehicles (some sources say 50 units, others say 57) equipped with a 427 cubic-inch version of the W engine. Officially designated RPO Z11 and offered at a price of $1240, the 427 obtained its bigger displacement via a 3.65-inch stroke versus 3.50 inches for the 409 and sported a whopping 13.8:1 compression ratio.
The Z11 also used the previously released big-port heads and two-piece intake manifold, and was nominally rated at 430 hp at 6,000 rpm, though it was capable of close to 500 hp. Not shown in the picture above is the cowl-induction air-intake housing pioneered by Chevrolet in 1963, although the cowl opening is just visible at far left. Running in NHRA’s A/Factory Experimental class in the ’63 season, Z11 Impalas ran elapsed times in the high 11-second range at nearly 120 mph.
Since it shares the same bore, stroke, and displacement, the Z11 is often confused with another Chevy racing engine of 1963, the famed Mystery engine (read the Mac’s Motor City Garage feature here). In truth, these are two rather different powerplants. For one thing, the Z11 was intended for drag racing, while the Mystery 427 was built mainly for NASCAR. However, both engines played significant roles in the development of the famed Mark IV big-block V8 introduced in 1965—but that’s another story.