Chevrolet raises the performance bar with big-block Mid & Full-Size models: 1966 CHEVY 396/427 MARK IV: BIGGER IS BETTER.
After teasing enthusiasts with a very-late and very-limited-production Z16 Chevelle SS powered by a proprietary 396/375 Mark IV big-block, Chevrolet followed up with a newly-styled ’66 Chevelle SS396 with less horsepower! First introduced with base 396/325 and optional L34 396/360 hydraulic-cam motors, it was a while before they quietly offered the L78 396/375 solid-lifter powerhouse that enthusiasts craved. It appeared in March 1966 with little fanfare or marketing support.
Except for displacement and advertised horsepower, the 396/375 and 427/425 were very similar. The 427/425 Mark IVs in the full-size Chevy Biscayne, Impala & Caprice and Corvette, and the 396/375 had four-bolt-main blocks, 11-to-1 compression, .520-inch-lift solid cams, rectangular-port heads with 2.19-inch intake valves and aluminum intake manifolds with 780-cfm Holley four-barrel carburetors.
Chevelle SS396 models were trimmed to appeal, and powered to impress Musclecar shoppers. All SS396 Chevelles came with rear frame reinforcements. We tested a 396/360 Chevelle with four-speed 3.73 Posi rear for the May 1966 Hi-Performance CARS and we were not that impressed.
Our best 0 to 60 was 8.0 seconds and couldn’t do better than 91 mph in 15.85 seconds on the track. Getting the power to the ground was a major problem. With sticky tires and 4.11s, high-mid-14s would be in reach.
For the full-story about 1966 CHEVY 396/427 MARK IV: BIGGER IS BETTER, check out OVER-DRIVE Magazine’s fact sheets on 1966 Full-Size Chevys @ https://over-drive-magazine.com/2024/08/26/1966-chevrolet-full-size-cars-fact-sheet/
For the full-story about 1966 CHEVY 396/427 MARK IV: BIGGER IS BETTER, check out OVER-DRIVE Magazine’s fact sheets on 1966 Mid-Size Chevys @ https://over-drive-magazine.com/2023/09/22/1966-chevrolet-mid-size-cars-fact-sheet/