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Engine Month: Today Is 427 Day! Celebrate the Chevrolet Big-Block!

Engine month is where we celebrate all the beautiful, big-displacement V8s.

Phillip Thomas Apr 27, 2016
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Today is April 27, or 427, which HOT ROD proclaims as 427 Chevy day!

The Chevrolet big-block is the workhorse racing engine of the muscle-car era. The 427 W first showed up midyear as a stroked 409 for the 1963 Chevrolet Impala SS. However, a year before, a little-known hot rodder named Mickey Thompson began testing the first true Mk II 427 “mystery motor.” The Mk II 427 big-block did not first race at Daytona, as the story went, but, in fact, Thompson would be the first to race the Mk II 427 with the 1963 NASCAR American Challenge Cup.

The 427 did well in competition, seeing use in the lanes of Pomona, the hills of Le Mans, and on the banks of Daytona. From 1966 through1969, Chevrolet put its biggest hammer in the Biscayne/Caprice/Impala, Corvette, and Camaro (as dealer-installed COPO packages). Iron or aluminum block—same choice on cylinder heads, one carb or three, and all manner of configurations—the 427 became the answer to just about any performance problem Chevrolet had at the time, and horsepower ranged from 390 to 450. The 427 also became the basis for the iconic 454 big-block and provided the foundation for many years of big-block service in both racing and truck applications for decades; it was only in 2006 that Chevrolet ended the big-block Vortec 8100, an 8.1L, 496ci throwback to simpler times. Hell, when it came time to revive a high-revving, NA engine for the then-new C5 Corvette Z06, Chevrolet again chose 427 ci—albeit in small-block LS7 form.

To celebrate 427 day, we’re throwing you some of our favorite 427 big-block stories—everything from how to build them, to what they raced in, and who hot rodded them:


002 1963 Corvette Mystery Motor 8826 Lpr 2/11

1. Mickey Thompson Z06 Mystery Motor Stingray

It’s rare for a magazine to be the impetus for someone to take a priceless racing engine and slide it into a million-dollar car, and honestly, when this idea came about in 2014 we were a little reluctant to even ask. It’s rarer still for a project of this magnitude to come together to celebrate the 50th anniversary of a production engine as storied as the big-block Chevy. But perhaps the greatest part of this tale is that every Chevy guy swears he knows how the big-block Mystery Motor first raced in an Impala at the Daytona 500 on February 24, 1963—and it turns out that’s totally wrong. The true story is the Mystery Motor actually made its racing debut a week earlier—and not in an Impala


003 6 1963 Mystery Motor Corvette Mickey  Thompson Daytona Lpr 3/11

2. Now It Can Be Told! The True Story of How Mickey Thompson Was the First to Race the Big-Block Chevy

Zora Arkus-Duntov’s high-performance engineering group was responsible for Corvette engineering and Chevrolet’s high-performance V8 development when the 348ci W-engine debuted for the 1958 model year. The solid-lifter version of the 348 with triple two-barrel Rochesters was rated at 315 hp (and was Chevrolet’s most powerful engine) while the Corvette’s fuel-injected, 283ci small-block was only rated at 290 hp. Duntov resisted putting the 348 into the Corvette, arguing its additional 100 pounds on the Vette’s front tires would compromise handling. By the time the second-generation Corvette Sting Ray came out for 1963, the W-engine had 409 ci and produced 425 hp with solid lifters and dual four-barrel Carters, but again, it wasn’t on the new Vette’s option list. Duntov didn’t feel the “fat block” 409 could pull its own weight. But there was a 427ci V8 on the horizon he would be happy with in a couple of years. Hot rodder Mickey Thompson, however, wasn’t going to wait.


004 427 Chevy Mystery Motor Dyno Test 007 4/11

3. WORLD EXCLUSIVE: We Dyno Chevy’s Historic 1963 427 Mystery Motor Built By Smokey Yunick

Dyno testing a one-off Chevy 427 Mystery Motor built by Smokey Yunick back in the 1960s was nerve-wracking, historic, and a rush. These Mark IIs 427s were the predecessors to Chevy’s infamous big-block engine. Guesstimates of how many were made range from 17 to maybe 50. Tom McIntyre’s is the only race-version of a Mystery Motor that exists. The Mark II is a mashup of both 409 W engine specs like bore spacing and bore/stroke—and its unique canted valve heads, more commonly called porcupine heads for the differing valve-stem angles you see with the valve covers off. Chevy built both a 409 Mark II, and a 427 Mark IIs, with the "S" standing for stroked. Among its many test bed purposes was evaluating the use of screw in rocker studs.


005 Ccrp 0910 01 Z Chevy L88 427 Engine 5/11

4. Chevy L-88 427 Engine - Horsepower!

Today, a 1,000hp power-adder street engine is almost commonplace. At this escalated power level, it's easy to forget that not all that long ago, a 500hp big-block Chevy was considered the holy grail of street runners. When Chevy replaced the aging W-engines with the MK IV big-block in 1965, it was the equivalent of Chevy landing D-Day troops on the shores protected by Ford and Mopar. The initial 425hp 427 engines in the Corvette were heavy hitters. By 1967, the Bow Tie brigade launched the L88 427 with then-unheard-of factory aluminum heads.


006 0707phrp 02 Z Chevy Engine Engine Block 6/11

5. Mark IV Family ZL1 Chevy Engine - History Of The Big-Block Chevy

The legend began on the high banks of Daytona in February 1963. A handful of Chevrolets arrived for the Daytona 500 with something mysterious under the hood. While Ford and Chrysler expected to compete against Chevrolet's venerable W head 409, the Bow Tie guys had a big surprise waiting for them. As Junior Johnson's Chevy thundered around the track at speeds in excess of 160 mph, every soul in the paddock, pits, and stands knew that was no W block. Hot on Junior's heels was Johnny Rutherford, in another Chevy. The Chevrolets of Ray Fox, Smokey Yunick, and Bubber Farr all ran with power unmatched by the 409, and Ford and Chrysler cried foul.


007 1967 Chevrolet Dana Camaro Prototype Front Three Quarter 7/11

6. The Amazing Story Behind the First Dana 427 Conversion of a 1967 Chevrolet Camaro

Every story has a beginning. For this first-year Camaro with a small-block V8, the story began with an early delivery from the factory to Brown & Hoeye Chevrolet in Mesa, Arizona, in November 1966. The new 1967 Chevrolet Camaro was a hot commodity already, and this example was purchased by a couple of guys who intended to give it some kick. It was here that the first-ever 427 Dana Camaro (DC1) made contact with infamy: Those two guys, Payton Cramer and Don McCain, worked at Carroll Shelby's place just 5 miles away.


008 1967 Chevrolet Crusher Camaro 489ci Big Block 8/11

7. 700HP Shootout: EFI LS7 vs. Blown Big-Block

The world needs another LS-powered early Camaro! It really doesn’t, but it seems no one in the performance industry got that memo, because guys are building the ubiquitous combo in soaring numbers and manufacturers are releasing new swap parts like popcorn. Holley is chief among ’em and has a complete line of LS-engine swap parts, including engine mounts, trans, crossmembers, oil pans, accessory drives, headers, exhaust systems, intake manifolds, fuel components, and EFI conversions. To prove how easily the late-model engine can be retrofitted into an old car with Holley parts, the company made a foolhardy gamble, sponsoring a challenge for us guys from the Roadkill show: we’d have to install an LS engine and EFI from scratch in three days in front of a live-video-feed audience, and do it from the floor of the Performance Racing Industry trade show. Immediately after the show, we’d have to drive the car 2,400 miles from Indy to California to escape December weather so we could drag race it. It’s as if no one at Holley had ever seen the level of fail that litters the plot of most episodes of Roadkill.


009 1966 Retromod 427 Bbc Super Sport Chevelle Front Quarter 9/11

8. This 427-Powered 1966 Chevrolet Chevelle Turns Heads

Ancient folklore in many ocean-going cultures tells of the siren’s song that charmed mariners with its hypnotic powers. During the golden age of muscle cars, the moan of a four-barrel carb in the evening’s distance had much the same effect. Danny Roddenberry remembered a similar call when he ran across this immaculate Super Sport Chevelle, and he’s been smiling ever since! “I’ve been involved in cars for 42 years,” Roddenberry recalled. “Ever since I was 16. I bought a 1957 Chevy when I was 18 and still have it, but I really wanted a ’66–’67 Chevelle when I was in high school. I couldn’t afford it. In fact, none of us could back then.


010 427 Chevy Mystery Motor Dyno Test Front 10/11

9. WATCH! The First Dyno Pull of Chevy’s Famous, 427 Big-Block Mystery Motor

Never has there been video of a Chevrolet 427 Mystery Motor running—heck, there are only two or three known engines left in the world. But HOT ROD has exclusive video of the 6,000-rpm dyno pull of Tom McIntyre’s prototype big-block Chevy Mystery Motor. Historic? Yes. But what now?


011 Ccrp 1004 01 O 1969 Car Craft Cover Bil Jenkins 11/11

10. How Bill Jenkins' 1967 Big Block Made Him Smile

Grumpy Jenkins’ drag-racing career began like many young men who grew up in the 1950s. In those days, Jenkins was known not as “Grumpy” (that came later, due to Jenkins gruff facade), but “Jiggs” Jenkins. A mechanical aptitude developed at an early age allowed him to quickly acquire an in-depth knowledge of engines. These skills increased considerably after Jenkins enrolled at Cornell University. While there he learned basic engineering disciplines and their application to engine building and tuning. Soon, other drag racers were eager to pay for the counsel and hands-on touch available from one Jiggs Jenkins.

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