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International 427 Day Is This Sunday!

Get Out & Enjoy Chevy's 7-Liter Powerhouse!

Scott Ross Apr 24, 2014
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Chevy lovers: Take a look at your calendar. Do you see what date is coming up this Sunday? 4/27, right...That means it's International 427 Day!

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Yes, it’s April 27th…4/27. What better day to celebrate that legendary Chevrolet big-block powerplant than by driving your 427-powered Chevy this Sunday, wherever in the world you are.

We’re urging those of you with Mark IV 427-powered steel-bodied Chevys—Camaros, Chevelles, Novas and full-size Chevrolets—as well as Corvettes and Camaros with the modern-tech LS7 427 under their hoods--to join in the fun, too!)

Here’s a note we received from the folks at Mid America Motorworks, urging Corvette lovers to take their ’66-’69 427-powered Midyears and Sharks out for a day of fun.

Get on the Open Road in Your Corvette for 427 Day Mid America Motorworks celebrates the iconic 427 big block engine on April 27th

In March, Mid America Motorworks paid tribute to the 327 small block, deeming March 27th “327 Day.” The aftermarket supplier and manufacturer of Corvette parts and accessories will once again be honoring an iconic Chevrolet engine this weekend with “427 Day.”

Development of the 427 big block started with the so-called “Mystery Motor” used in Junior Johnson’s 1963 Daytona 500 record-setting Impala Super Sport stock car. This "secret" engine was a substantially modified form of the previous W-series 409 engine. In mid-1965, it was subsequently released for production use as the Mark IV, referred to in sales literature as the "Turbo-Jet V8." The 427 soon became known to automotive journalists and enthusiasts simply as the “Rat,” playing off the popularity of its 327 little brother, the “Mighty Mouse.”

The 427 was introduced as an engine option at the beginning of 1966 Corvette production. A variety of single- and multi- carburetor options, camshaft, cylinder head, intake, and compression ratio combinations would yield 7 unique 427 engine packages:

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The rugged dependability and performance of the 427 ensured an extensive role in Chevrolet and GMC Commercial vehicles, in addition to numerous marine applications. In 2006, the 427 entered the new century, as the LS7 505HP 427 was called upon to propel the 6th Generation Corvette Z06 model. Although the LS7 427 is a small block variant sharing very little with its 1960s big block ancestor, it proudly carries the Corvette 427 flag.

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Mid America Motorworks has created a video on one of their favorite 427 Corvettes, the 1968 Le Mans Corvette, available here: http://youtube/XE4kUbcOdss They are inviting all fans of the “Rat” to share their own 427 stories on a special Facebook page https://www.facebook.com/events/485072104955718/ , and spread the word about 427 Day to all 427 owners, former owners and enthusiasts.

Other 427-related items:

-Those factory horsepower ratings for the 1966 427s were cut from their original 400 hp (for the L36) and 450 hp (for the L72), after The 14th Floor got a case of nerves over engines with so high a horsepower rating. Chevrolet’s solution? New stickers for those engines’ air cleaners with the lower ratings. Those weren’t the peak numbers, though…just ones taken from a little ways down the HP curve, enough to soothe the “nervous Nellies” then in GM’s upper management, including those who killed all racing-related activities company-wide soon after the ’63 Daytona 500. (But they didn’t kill off Chevy’s “Product Promotion Engineering” department!)

-You can thank the folks at HOT ROD Magazine for the “Mystery Motor” name, which first appeared on a banner blurb on top of their May, 1963 issue (“SCOOP! Chevy’s NEW 427 Mystery V8”), where they reported on this never-before-seen Chevy V8 that powered the ’63 Impalas of Junior Johnson, G.C. Spencer, Johnny Rutherford, Rex White, and Bubba Farr in that year’s 500.

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All hail Chevrolet’s 427s on Sunday, International 427 Day. (This one’s inside the engine bay of a ’69 Camaro Yenko Sport Coupe.

So, be sure to enjoy your 427s on Sunday…and don’t forget to post a picture of yours here!

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Yes, modern-day Chevys with 427 power are worth celebrating on International 427 Day, too…like the new Camaro Z/28!

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If you thought the days of Chevy’s’ 427s ended with the arrival of the 454s, think again! Here’s a look at the 427 that powered the Camaro Z/28 seen above.



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