Throughout the ’60s muscle car era, the Chrysler 426 Street Hemi resided at or near the top of the heap at the drag strips and drive-ins of America. Here’s a quick look back. 

There’s a claim we frequently hear from auto manufacturers around the world: That the engines in their showroom production cars are close relations to their championship-winning racing engines. Often there’s not much fact in these assertions, sometimes none at all, but we can think of one example where it was no idle boast. Chrysler’s mighty 426 Street Hemi of 1966 through 1971 was but a mildly detuned version of the 426 Race Hemi that was frequently seen in winner’s circles from Daytona to Pomona.

The Street Hemi (1970 cutaway shown above) came to be when Chrysler was behooved to demonstrate to racing’s rules-makers in NASCAR, NHRA, and elsewhere that the 426 Hemi was indeed available to the general public. So in January of 1965, a program was launched (internal designation A102) to create a production road version, with special focus on  the ’66 Plymouth and Dodge model year introductions in the fall, and the alterations were surprisingly minor.

Bore and stroke were 4.25 by 3.75 inches, same as the race engine, while the block, heads, and architecture were nearly unchanged.  To allow the beast to tolerate civilian pump gasoline, the compression ratio was reduced from 12.5:1 to 10.25:1, and to aid cold driveability a manifold heat-riser system was added. For ease of packaging and tuning, the crossram intake manifold setup was set aside and an inline intake manifold (based on the NASCAR single-quad manifold’s dual-plane layout) was used, supporting a pair of Carter AFB four-barrel carbs.

While the cam timing was dialed back for street use, it was still fairly sporty with 292 degrees of duration and 68 degrees of overlap. All along, Chrysler’s plans had included a hydraulic cam to simplify maintenance, but it didn’t appear until the 1970 model year. The ’66-69 Street Hemis run solid lifters like the Race Hemi. And that’s just about it. Beyond that, the Race Hemi and the Street Hemi are remarkably similar animals.

Along with its impressive performance, another key part of the 426 Street Hemi’s image is its imposing appearance. The big, wide V8 with its enormous valve covers tends to fill the engine compartment of most any car it is crammed into. One key decision back at the beginning by Chrysler perfomance boss Tom Hoover and his engineering team made that possible. When they developed the 426 Race Hemi, adapting the Hemi combustion chamber architecture to the B/RB wedge-head V8, they rotated the cylinder heads a few degrees inward on both sides so the complete engine would just slip between the rails of the Chrysler B-body platform.

As things turned out, this minor compromise in the cylinder head design made no discernible difference in performance. The Street Hemi version was rated at 425 hp at 5000 rpm, and it typically made more than that in purely stock tune simply by winding it a little higher, but Chrysler lowballed the number for marketing and political reasons. Offered as a 900-buck package that included a heavy-duty New Process 4-Speed manual or Torqueflite automatic transmission and uprated rear axle (Mopar 8 3/4 for the automatic, Dana 60 for the stick) the Street Hemi option wasn’t cheap, but it was still the deal of the century. At drive-ins and drag strips across the country, the Street Hemi was muscle car royalty, granting its owners instant status at or near the top of the heap.

Through no fault of its own, the Street Hemi was discontinued in 1971. The muscle car era was ending due to rising insurance rates, tougher emissions laws, and changing times. Chrysler attempted to carry on with a lower-cost, volume-production version of the Hemi, but due to rapidly changing market conditions it never received the green light for production. (Read about the Chrysler Ball-Stud Hemi V8 here.) The Hemi name lives on, however, in Fiat Chrysler’s current lineup of performance V8s, including the 717-hp Hellcat and the 807-hp Challenger Super Stock.