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Corvette Mystery Motor celebrated on Mid America Motorworks 427 Day

Mid America Motorworks has proclaimed April 27th 427 Day
Mid America Motorworks has proclaimed April 27th 427 Day
Mid America Motorworks

Last month Mid America Motorworks had so much fun “rekindling fond memories with Covette 327 Day,” that they havre decided to celebrate 427 Day this Sunday (April 27th) to honor the iconic Chevrolet engine. Called “The Mystery Motor,” when first used to power Junior Johnson’s 1963 Daytona 500 record-setting Impala Super Sport stock car, the 427 big-block was a majorly modified form of the previous W-series 409 engine. It was later released for production use in mid-1965 as the Mark IV, referred to in sales literature as the "Turbo-Jet V8." “playing off the popularity of its 327 little brother the ‘Mighty Mouse,’” according to a company spokesperson, who also noted that the press (as well as auto enthusiasts) at the time later dubbed it the “Rat.”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 including::

First Year Last Year Engine Code Features Compression Ratio Factory Gross Power Rating
1966 1969 L36 4-barrel 10.25:1 390hp; 1966 1969 L72 4-barrel + solid lifters, more aggressive cam and high flow cylinder heads 11.00:1 425hp; 1967 1969 L68 L36 with 3x2-barrel carbs. 10.25:1 400hp
1967 1969 L71 L72 with 3x2 barrel carbs. 11.00:1 435hp; 1967 1969 L89 L71 + aluminum heads; RPO L89 also applied to L78 "375 HP" 396 engine with aluminum head option. 11.00:1 435hp; 1967 1969 L88 Racing-spec cam, high-flow aluminum heads (casting #s varied by model year) and some upgraded, competition-grade parts 12.50:1 430hp; 1969 1969 ZL1 Aluminum block with open chamber "3946074" aluminum heads; cam even "hotter" than L88's, and upgraded parts similar to L88's 12:00:1 430hp

Like the “Mouse” small block, the 427’s rugged dependability and performance ensured an extensive role in Chevrolet and GMC Commercial vehicles, in addition to numerous marine applications. Super Chevy Magazine even named 3 variants of 427 as the number 7, 8 and 9 best engines ever made by Chevrolet!History repeats itself in 2006, 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 in the new century. Readers are invited to share their own stories about the Chevy 427 on the Mid America Motorworks Facebook page. For more information visit