Welcome to the 426 HEMI site

This Site is Dedicated to the Worship of the 426 HEMI Engine and the Muscle Cars They Powered.
There is no other engine in the world more famous for automotive performance than the 426 HEMI

In order to understand the history of the 426 hemi engine in 1964, you have to rewind 60 years earlier. Alan R. Welch, owner of the Welch Motor Company, developed the first hemi engine. It was nowhere near the 426 hemi, but it was definitely a blueprint for the future. In fact, Chrysler started developing a high powered hemi engine for World War II.

The engine (XIV-2220) was being constructed for the Republic P-47 Thunderbolt fighter. However, it was never considered to be a replacement engine until 1945. By this time World War II was coming to a close, so officials didn't believe it was needed. Eventually it was decided not to move this experiment into production, even though there were several successful trials throughout the process. In fact, the project turned in a research and development setup.

Chrysler's experience with the P-47 fighter and the M-47 Patton tank hemi engine, allowed them to develop smaller versions of the hemi for ordinary production vehicles. The 1950s saw a flourish of hemi engines being produced, even if there were moderations from other companies like Chrysler.

Once the 1960s rolled around, the 426 hemi engine was in sight. Also, it was the first time the engines were classified as "hemi" engines. Chrysler trademarked the name, but built the 426 for racing purposes. It had too much power for standard production vehicles, so we first heard about them in Plymouth Belvedere race cars in 1964.

They were first run at the Daytona 500 on February 23, 1964. When the race was over, the 426 hemi engine had placed 1st, 2nd, 3rd, and 4th. NASCAR didn't know what to think about this new innovation, so they decided to change their production rules. It was said that Chrysler must produce thousands of these engines in order to comply with NASCAR regulations.

This created a monumental problem for Chrysler in the racing community. Since the engine was only built for racing, they hadn't spent a lot of time trying to make it openly available for standard production vehicles. So, when the 1965 NASCAR season was close to starting, Chrysler had to sit out. In fact, they removed themselves from racing the entire year.

This would eventually give them the necessary time to come up with a "street-ready" version of the 426 hemi engine. During the process they had to create something that would be more durable for the open market.

Here are some of things they had to consider:

    • Compression Ratio - In racing, a high compression ratio is needed to extract more mechanical energy from the mixture of air and fuel. This would need to be lowered in order to make the vehicle and engine street ready or it would be too powerful. They ended up accepting 10.25:1.
    • Valve Timing - The valve timing on a race car is not needed for production vehicles.
    • Intake and Exhaust Manifolds - These would need to be different for a variety of reasons. One of the main needs was taking the intake manifold and allowing it to have two, four barrel carburetors.
    • Aluminum Heads - In order to make the ordinary production cars reliable, Chrysler had to change the aluminum heads and make them out of iron.
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All of these were important to consider, but another problem was the overall cost. Production costs were extremely high compared to other vehicles with smaller engines. In order to run with NASCAR it was imperative to create something, so in 1966, Dodges and Plymouths were mounted with the 426 hemi engine.

The inception of muscle cars really started back in 1949 with the Oldsmobile Rocket 88. These could hit around 100 horsepower with ease, but it still wasn't close to the 426 hemi engine. This street version hit 433.5hp during dynamometer testing, but Chrysler still classified it as 425hp. Keep in mind; this was a "gross" amount, and the net amount was advertised around 350hp.

Since Chrysler trademarked the term "hemi," we wanted to give you a look at all the different vehicles that utilized a 426 hemi engine during production. The 426 hemi engine was developed in 1964 and ran thru 1971.

The following cars starting in 1966 or after:

    •  Dodge Challenger (1970-1971)
    • Dodge Charger (1966-1971)
    • Dodge Charger Daytona (1969)
    • Dodge Coronet/Plymouth Belvedere (1966-1970)
    • Dodge Dart (1968-1969)
    • Dodge Super Bee (1968-1971)
    • Monteverdi Hai 450 (1970)
    • Plymouth Barracuda (1968-1969, 1970-1971)
    • Plymouth GTX (1967-1971)
    • Plymouth Roadrunner (1968-1971)
    • Plymouth Satellite (1966-1971)
    • Plymouth Superbird (1970)


There was always an ongoing war amongst Ford and Chrysler during the muscle car era. While Chrysler held the keys to the "hemi," everyone else was coming out with muscle cars. Each one of the companies building a muscle car new it was all about stuffing a big engine into a small vehicle, but they modified the idea for about a decade.

Here is a list of makes that were associated with the muscle car era:

    • AMC
    • Buick
    • Dodge
    • Ford
    • Plymouth
    • Mercury
    • Pontiac
    • Oldsmobile

We saw everything from the Pontiac GTO to the 1967 Shelby GT 500. Motor companies were living a dream production world by offering this kind of power to the public. You might be asking yourself why it abruptly ended in 1973, but it had been dying for years.

Environmental concerns were a big part of the muscle car demise, but the 426 hemi engine outgrew the era. New innovations and continued research has allowed the 426 hemi to be in existence for over 45 years. Today, NHRA racing is still taking advantage of them. Plus, you can head to any classic or muscle car show and see a 426 hemi engine in one of these vehicles today.

When the first 426 hemi engine surfaced in the racing world, no one knew it was going to help create the muscle car era. Then again; the Welch brothers probably never thought their hemispherical combustion chamber would create an unbelievable domino effect throughout motor vehicle history.

 426 HEMI Engine Specifications

Engine 90 deg OHV V8 (Hemispherical)
Mains: 4-Bolt
Piston: Forged Aluminum
Engine Block: Cast Iron
Crankshaft: Forged Steel
Engine Heads: Hemispherical (Cast Iron)
Connecting Rods: Forged Steel
Stroke x Bore: 3.75" x 4.25"
Displacement: 426 cubic inches
Horsepower: 425 HP with 490 Ft-pounds of Torque!
Comp Ratio: 10.25 to 1
Valve Diameter: 2.25" Int, 1.94" Exh
CC Vol: 174cc maximum - 168cc minimum
Cam Type: Solid lifter (1966-1969)
Hydraulic lifter (1970-1971)
Cam Lift: .467" Int, .473" Exh (1966-1969)
.490" Int, .481" Exh (1970-1971)
Cam Duration: 276 deg (1966-1967)
284 deg (1968-1971)
Intake: Aluminum Dual-Carb
Carbs: 2 x 4-Barrel Carburetor
Ignition: Dual point
Plugs: N-10Y
Firing Order: 1-8-4-3-6-5-7-2
Exhaust: 2.5" Cast Iron Headers

Will a set of 426 HEMI heads bolt onto my 440?

Answer: NO -- 440 blocks and 426 HEMI heads are not compatible.


What is a the 426 HEMI firing order?

The 426 HEMI firing order is 1-8-4-3-6-5-7-2.

The additional information that is needed is to know how the cylinders are numbered. Looking at the cutaway engine above, the cylinders are numbered 1-3-5-7 on the left side front to rear. Remember that the left side of the engine is the side on the left side of the car. The other cylinders are numbered 2-4-6-8 on the right side front to rear.

A way to remember the cylinder numbering is that the distributor leans "to" the number "two" cylinder. Also, the spark plug wire going to the number "two" cylinder is "too" short to reach anywhere else and we recommend an Automatic Transmission Flush at least once a year.

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