With the introduction of the 426 Max Wedge
in 1963, the 413 Max Wedge was dropped from the Dodge and
Plymouth lines, but the 413 in milder states-of-tune remained
available in Chrysler cars. For 1963, you could order a single
four-barrel 413 developing 340 hp at 4600 rpm and 470 pounds-feet
of torque at 2800 rpm. Compression ratio was 10.0:1. There was
also a dual four-barrel setup that developed 390 hp at 4800 rpm
and 485 pounds-feet of torque at 3600 rpm.
There were three 413's to choose from in 1964. The single four-barrel unit had the same specs as the year before, except for a slightly higher compression ratio of 10.10:1 There was also another four-barrel 413 with 360 hp at 4800 rpm and 470 pounds-feet of torque at 3200 rpm. The dual four-barrel 413 suffered a drop in compression to 9.6:1, but it still pumped out 390 hp and had a higher torque rating than even the 426 Max Wedge.
The dual four-barrel 413 was dropped in 1965, leaving two 413'S with single four-barrel carburetion. Horsepower and torque readings were the same as the year before, but Chrysler fiddled with the compression ratio again, returning to 10.0:1. This was the last year of the 413's production.
The 413 was really Chrysler Corporation's first drag racing engine, putting Dodge and Plymouth on the performance map and capturing the attention and interest of all enth usiasts. This engine has a special place in the hearts and m inds of Ch rysler eng i neers and executives as well as Mopar fans.
The 426, also with a wedge cylinder head design, first appeared in 1962, installed only in top-of-the-line Chryslers. It was not available in Dodges or Plymouths. This engine was not a high-performance powerplant in the drag racing sense. But this changed in 1963, when Chrysler introduced the 426 Max Wedge Stage Il engine. The primary difference between this engine and the 413 Max Wedge, of course, was the larger bore of 4.25 inches, resulting in 426 ci.
The 426 Max Wedge was strictly designed for racing, and was offered in Plymouths as the Super Stock 426 and in Dodges as the 426 Aamcharger (the spelling was changed). Aside from the displacement, the visual differences between the 426 and 4~3 Max Wedge engines were slight. A Plymouth brochure showed its Super Stock 426 with a black, seven-blade fan. A Dodge brochure showed its 426 Ramcharger with a chrome, fourblade fan. In every other respect, the two were identical.
Like the 413 Max Wedge, the 426 Max Wedge was available with a choice of two compression ratios. The 11.0:1 engine developed 415 hp at 5600 rpm with 470 pounds-feet of torque at 4400 rpm. The 13.5:1 engine developed 425 hp at 5600 rpm and 480 pounds-feet of torq ue at 4400 rpm. Based on these fig ures, the 426 Max Wedge developed on ly five more horsepower and five pounds-feet more torque than the 413 Max Wedge. The elapsed times and trap speeds of Mopars running the 426 Max Wedge were no better than those for the 413 Max Wedge. Tom Grove, racing for Melrose Motors in Oakland, Calif ornia, switched from the 41 3 to the 426 Max Wedge, but did not improve his times by doing so.
In 1464, Chrysler introduced the 426 Max
Wedge Stage III. Improvements included larger-capacity Carter
carburetors and larger air cleaners to accommodate them: a new
camshaft with 320 deg rees of overlap: modified combustion
chambers with deeper clearance notches around the valves; 13.0:1
pistons replaced by 12.5:1 pistons in the higher-compression
engine: and new exhaust manifolds designed for NASCAR racing with
tuned, equal-length twenty-one-inch passages, which dumped into
two large steel tubes and then funneled into a 3'/2-inch-diameter
head pipe on each side. Chrysler referred to this exhaust
manifold system as Tri-Y headers.
With the introduction of the 426 race Hemi in 1964, racers had an even more powerful engine to use. The Hemi was designed to surpass the 426 Max Wedge, but the Hemi's production was limited, so the 426 Max Wedge remained a viable and affordable alternative. The 426 Max Wedge stayed in production through 1964.
There also was a street version of the 426 in 1964, but it lacked virtually all the Max Wedge components--with good reason. While you could walk into any Dodge or Plymouth dealer and order your Mopar with a 426 Max Wedge, the trouble started when you took delivery and tried to drive it home. The engine was almost undrivable on the street: the 426 Max
Wedge was a racing engine, pure and simple.
The 426 street wedge, while lacking the power of its snarling
brother, also had none of the headaches.
The 426 street wedge had one four-barrel carburetor mounted on a cast iron intake manifold, and had provision for crossover heat to the manifold to aid warmup. The exhaust manifolds were conventional--not the wildly shaped units used on the Max Wedge. Compression was a healthy 10.3:1. Horsepower was 365 at 4800 rpm with 470 pounds-feet of torque at 3200 rpm.
The last year for the 365-hp 426 street wedge was 1965. Mopar fans who dreamed of having a 426 street Hemi derived from the 426 race Hemi would not have to dream much longer.
Legendary is a word often bandied about when it comes to cars. If any engine earned this label, it was the 426 Hemi.
On February 23, 1964, three Hemi-powered Plymouths and a Hemipowered Dodge swept the Daytona 500, 1-2-3-4. It was a stunning victory which set the world of NASCAR racing on its ear. News of this awesome engine spread like wildfire.
As most Mopar enthusiasts know, the 426
Hemi was not the first Chrysler Hemi, but it was the best.
Whereas the Hemis of the fifties were passenger-car engines, the
426 Hemi of 1964 was conceived strictly as a race engine, from
the oil pan up. Its purpose was to win big on the NASCAR circuit
and dominate organized drag racing.
Chrysler met the letter of the law in the NASCAR rule book with regard to the minimum production run of engines. However, the 426 Hemi was too successful for its own good. It was making a mockery of the competition, and NASCAR put its foot down. Instead of building several hundred blue-printed Hemis a year, Chrysler had to build several thousand and offer them in production vehicles. Chrysler had invested too much time and money developing the Hemi to walk away from NASCAR permanently (although it d id so for one year); the company turned a liabi lity i nto an asset and detuned the Hemi for the street.
The street Hemi was introduced in 1966 in the Plymouth Belvedere and Dodge Coronet and Charger. When you compare the specifications of the 1964, 1965 and 1966 track and drag engines with the 1966 street engine, it's startling how similar they are. Only modifications to make it drivable on the street were made. The street and race Hemi had the same cast iron, stress-relieved block with a bore and stroke of 4.25x3.75 inches. The forged, shot-peened and Nitride-hardened crankshaft was the same for both street and race Hemi, as well as the impact-extruded pistons, crossbolt main bearing caps, forged connecting rods, iron cylinder heads and mechanical lifters.
The biggest differences between the street
and race Hemi were the intake and exhaust manifolds. The intake
manifold on the circle-track Hemi in 1964 and 1965 was a
conventional aluminum dual-plane, single fourbarrel manifold. The
track Hemi of 1966 used an aluminum plenum-ram single four-barrel
manifold. For drag racing, the 1964 Hemi used an aluminum dual
four-barrel plenum-ram manifold. The 1965 drag Hemi used the same
manifold, but it was cast in magnesium; and to reduce weight even
further, it used aluminum cylinder heads. The exhaust manifolds
on the race Hemi were naturally of the header type, using
2'/r-inch-outside-diameter tubi ng with steel casti ngs or plates
bolted to the cyl i nder heads. Length varied from thirty to
forty inches.
The street Hemi had necessarily milder valve train specifications. The camshaft had both intake and exhaust durations of 276 degrees, compared to the 1966 track Hemi's 328 degrees. Valve overlap was fifty-two degrees on the street engine and 112 degrees on the track engine. Intake and exhaust valve lifts were 0.48 inch and 0.46 inch, respectively, while the track Hemi had 0.565-inch lift for both intake and exhaust. The valve springs were softer on the street Hemi to reduce camshaft wear. Racing valves were used in the street Hemi with an intake valve diameter of 2.25 inches and exhaust valve diameter of 1.94 inches.
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