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  1. #1
    Join Date
    Dec 2008
    Motor City
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    Inside the Beast - How the 1964 426 Race HEMI® changed everything

    By David A. Hakim

    It’s been wreaking havoc for 50 years with no signs of slowing down. The venerable 426 HEMI® has set numerous records in all sorts of racing classes and it still sends shock and awe through the competition. What is it about this engine that has endeared it to racers and fans for over a half century? Let’s go inside the beast of the 1964 426 Race HEMI for a quick look at what made it a legend.

    In the early 1960s, Chrysler was looking to be a serious player on the NASCAR ovals and the NHRA and AHRA drag strips across the country. With the success of the 413 and 426 Max Wedge, Chrysler’s engineers knew Ford and Chevrolet would be developing some serious ammunition and hunt them down on race day. While the Max Wedge was a killer combination for the drags, it still lacked the stamina needed to compete on the high banked ovals for 500 miles.

    Therefore, in March of 1963, a group of dedicated, passionate gearheads led by Tom Hoover began developing a new engine within hallways of Chrysler engineering labs nestled in Highland Park, a city within the borders of Detroit. Their herculean assignment was handed down by senior level directors within Chrysler’s board room - develop an engine that can win the 1964 Daytona 500. Thus the Advance Engine Group went to work immediately as they had less than 10 months to complete their task.

    The first order of business was engineering a new cylinder head that could provide the volumetric efficiencies in both combustion and airflow. Remember, the internal combustion engine is basically an air pump. The quicker you can get the air fuel mixture in and out, the more power it makes. What Tom Hoover and team did was revisit an old friend, the HEMI head design from the 1957 392 HEMI that powered a 2 ½ ton tail finned Chrysler 300 to new land speed records on the beach at Daytona. Since the design was a huge success on the first generation HEMI engines, maybe it the basic layout could still be applied. After all, the first HEMI style cylinder head used in an engine was developed in World War II for aircraft so there was a lot a research and development on the heads attributes.

    Tom Hoover realized that a 10 degree rotation of the chamber would fix
    geometry and vehicle fitment issues on the new 426 HEMI.

    Even with the 392 HEMI head as a guide, a major overhaul was still needed for a number of reasons – more to come on that later. The assignment of making wholesale changes to the head fell to lead designer Frank Bialk. Frank used the same 58 degree angle between the intake and exhaust valve centerlines on the original Chrysler Fire Power HEMI engine but make other changes in the port design. Remember, these guys were up against a wall and there was no time to look at other cylinder head chamber layouts. However, it was Tom Hoover that realized if the combustion chamber was titled 10 degrees, the valve gear ratio would be in proportion and the HEMI head would fit inside the Dodge and Plymouth B-Body inner fenders.

    By utilizing the existing 426 Wedge block with some modifications and changing the
    HEMI cylinder head chamber angle, the new 426 Race HEMI fit nicely into the intermediate
    Dodge and Plymouth models.

    The new HEMI head was also designed to be installed on the existing 426 Wedge block. However, there had to be some changes. First, the Wedge block had to be modified for pushrod clearance. Second, the Wedge block had deep skirts which allowed the engineers to incorporate new cross-bolts in the number 1, 3 and 4 main bearing caps for added bottom end strength for the crank. With the projected sustained high RPM usage the HEMI was to see in NASCAR, the rotating assembly had to be tough and stable.

    The HEMI also needed a special piston to fit within its unique chamber so extruded aluminum ones with a 0.755 dome slipped on to forged steel I-beam connecting rods were also used. All this yielded a compression ratio of 12.5:1 requiring nothing less than 100 octane race fuel to feed the carburetors. Utilizing the bore size of 4.25” and a stroke of 3.75” from the 426 Wedge engine, the new 426 HEMI was about to be born and ready hit the race tracks.

    Making a better bullet within 10 months that would win races and championships
    was the goal the Chrysler engineers. Needless to say, they succeeded.

    To take advantage of the HEMI engines enhanced breathing capabilities, a solid lifter, long duration, and high lift camshaft was specified along with special tubular steel headers with cast-steel flanges made sure everything was happy at 7000 RPM. Topping this beast were two styles of intake manifolds and carburetor set ups. For drag racing, a pair of Holley 4160s (Carter 3816S where used on early production versions) were mounted on a ram-tuned, cross ram, one-piece two four-barrel intake manifold. On oval track HEMI engines, NASCAR rules dictated the use of a single Holley carb on an aluminum intake manifold.
    The two Race HEMI power plants also had different compression ratios and camshaft specs that lead to the different horsepower ratings - 415 and 425. Regardless, the HEMI’s true rating was north of 500 HP whether it was used in a quarter-mile sprint or 500 miles of banging fenders. One thing is for sure, 426 HEMI destroyed its competition during the 1964 race season and beyond.

    The 1964 426 Race HEMI looks like it’s ready to pounce in this glamour shot.

    Tom Hoover and his merry band of engineers had done their job as HEMI power claimed the first, second and third place finishes at the ’64 Daytona 500 with Richard Petty getting the trophy and the big check. HEMI power also claimed major victories in various drag classes with the pinnacle being an all HEMI Dodge SS/A final at the prestigious ’64 NHRA U.S. Nationals at Indianapolis.

    The Ramchargers was a clandestine group of Chrysler engineers that developed,
    raced, set records and won numerous events with HEMI powered Dodge vehicles.

    So dominant was the HEMI during its debut season, NHRA and AHRA had to juggled classes and horsepower factors to give the factory backed Ford teams a fighting chance and over in NASCAR, the officials just banned (some would claim “outlawed”) the HEMI for the 1965 season until a street version would available to the general public.

    That would be 1966 but that’s another story for another time so stayed tuned.
    Last edited by David A Hakim; 04-25-2014 at 01:44 PM.
    Thanks FlaCharger, ChuckWagon thanked for this post

  2. #2
    Join Date
    Jan 2006
    Kingsport, TN
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  3. #3
    Join Date
    Dec 2013
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    great refresher and the 60's & 70's was when Nascar was Nascar, nowadays no thanks.
    Likes BlackAce, MagnumClub liked this post

  4. #4
    Join Date
    Dec 2008
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    Nice write up. I never realized that the compression was that high in that year.
    2006 Charger Brilliant Black R/T w/R&T Package, 6.1 Arrington based 426 Hemi @ 13:1 compression 2016 Hellcat Charger rear cradle and brakes swap, DSS 4" custom driveshaft, 3.09 Scat Pack rear diff.
    Thanks Bsp16 thanked for this post

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