Chevy’s “Mystery” 427: A New Big-Block Heralded Engines To Come

 

Chevrolet called it their “Mark II” big block V8, designed and engineered to race — and win on NASCAR’s high-speed ovals. (Courtesy GM Media)

When it arrived at the Daytona race in 1963, it looked like no other Chevrolet engine before it. With its arrival came the prospect of a Bow Tie engine that could go toe-to-toe with Pontiac and Ford on the high-speed ovals that graced NASCAR’s schedule back then—Atlanta, Charlotte, Darlington, and the longest — and fastest one, Daytona.Junior 63

Chevy had won there before, with Junior Johnson wrestling a year-old ’59 Chevy two-door post sedan around the 2 1/2-mile oval, and discovering how to make the best use of the slipstreams that form at high speed. Three years later, Junior and car owner Ray Fox were back with another Chevy — a new Impala hardtop with a 427 cubic-inch V8 that shared little with the Z11 427ci engines that Chevy was readying for the 1963 NHRA Stock/Super Stock drag racing season. This engine was different than the “W-head” engines, starting with the wide valve covers that concealed what some observers called a “porcupine” valve layout, where each valve favored the port feeding it.

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In his May, 1963 feature for Hot Rod Magazine, Ray Brock said that meant that each valve head opened away from the combustion chamber and cylinder walls, for better flow. The new 427 cubic-inch engine also boasted a “ram air” set-up that used the air box under the factory cowl vent and a special air cleaner, to force more air into the engine, thanks to the low-pressure area at the bottom of the windshield. (Anyone care to guess what Chevy did with that idea?)

Exhaust used cast-iron manifolds that looked like headers. They featured 2-inch primaries. Courtesy Hot Rod Engine Tech

Brock noted that it was some 50 pounds lighter than a Z11 427ci engine, while only outweighing the Corvette Sting Ray’s fuel injected 427ci engine by only 49 pounds.

Here’s a look at the Mark II with the valve covers, carburetor and air cleaner off, showing the “porcupine” arrangement of the intake and exhaust valves, which carried over to the production Mark IV big block that entered production two years later. Intake manifold is a dual-plane high-riser, and the distributor is a single-point unit. (Courtesy Hot Rod Engine Tech)

Here’s a look at the Mark II with the valve covers, carburetor, and air cleaner off, showing the “porcupine” arrangement of the intake and exhaust valves. This design  carried over to the production Mark IV big-block that entered production two years later. Intake manifold is a dual-plane high-riser, and the distributor is a single-point unit. (Courtesy Hot Rod Engine Tech)

When the five ’63 Impalas running the new engine took to the track, the records fell. Junior Johnson won the ’63 Daytona 500’s pole with a new record speed of 160.943 mph, and then set another record in winning the first 100-mile qualifying race averaging 164.083 mph.

But those 427ci engines weren’t ready to run 500 miles wide-open, yet. Bubba Farr’s number 71 Chevy dropped out with a broken fuel pump on lap 22. Four laps later, Johnson’s day ended when his 427’s distributor broke. Junior’s teammate, G.C. Spencer, brought out the yellow flag when his number 03 car’s 427ci engine let go on lap 95. This left only two new Chevys to finish the race — 1960 Grand National champ Rex White’s number 4 Chevy, and Johnny Rutherford in Smokey Yunick’s number 13 Impala, which finally finished ninth, four laps behind winner Tiny Lund.

But the 100-mile qualifier was to be the “Mystery V8’s” swan song. Just days before the 500, GM Chairman Frederic Donner decreed that no GM division could actively support any form of auto racing, rededicating the company to the spirit of the 1957 agreement by the Automobile Manufacturers Association (AMA) to stop factory race-team support.

 

That threw the Chevy teams for a huge loop. No more parts would be coming from Chevrolet, so they would have to carefully pick and choose which of the 48 remaining NASCAR Grand National races they would run for the year. Junior Johnson’s final tally for 1963, saw him run 33 races with seven wins, 13 top-five finishes, and 14 Top 10s. He also had pole starts, and altogether, he placed 12th in the final Grand National points standings.

Ray Brock predicted, “You can bet that Ford and Chrysler Corporation are going to get busy in the engine department to see what they can come up with that’s just a little stronger. Chevrolet may have just performed a nice service to enthusiasts favoring the other camps. They can undoubtedly look forward to better engines, too.”

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