1963: Bunkie Knudsen Produces New Mark IV Big Block
by Scott Teeters as written for Vette Views
January 4, 1963 – GM President and Chief Operating Officer, Jack Gordon, gives Chevrolet General Manager, Semone “Bunkie Knudsen”, approval to proceed with an all-new big-block engine to replace the W-Series 409/427 engine
Dateline January 2016: When you think of “big-block” Chevy engines, the Mark IV, aka “Porcupine,” Rat Motor” usually first comes to mind. But the first Chevrolet “big-block” was the W-Series truck engine that was in production from 1958 to 1965 – only eight model years!
We have over two dozen 1965 Corvette Sting Ray art prints, similar to this one in our Etsy store HERE!
There were three versions of the old W-Series big-block: the 348 for light truck use, the 409 for Impalas, and the 427 (RPO-Z11 for drag racing) with 430-hp and an astonishing 575 lb-ft of torque. Even though the number for the Z11 looked good on paper, the W-Series engine just couldn’t compete against the big Ford and Chrysler Hemi engines. Chevrolet absolutely needed a new big-block design.
When the Mark IV was completed and released, Chevrolet was forced to adhere to a GM mandate that restricted engine sizes for production passenger cars to less than 400 cubic inches. The Mark IV was designed and intended to be a 427, so to comply, the bore was reduced from 4.251 inches to 4.09, making the engine officially a “396”. The big-block 396 was first offered in the 1965 Corvette.
When the big-block was bumped to 427 cubic inches for 1966, Duntov joked that the reason was the weight reduction of boring out an additional 31 cubic inches of iron.
The man had a sense of humour! – Scott
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