The Mark IV big block was the culmination of Chevrolet's performance engine development. Introduced in 1966 as a production engine option for full-sized Chevrolets, the highly versatile 427 cubic inch big block terrorized local drag strips and gave high performance engines a new standard. The success was short lived due to fuel shortages and emission standards. But fear not! The horsepower happy big block lives on and Speedway Motors is your source for performance parts and accessories for your 427 Chevy engine.