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Thread: gen iv ,v,or vi question

  1. #1
    Member JUNIOR BUILDER
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    Jan 2006
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    gen iv ,v,or vi question

    on a bowtie bbc how do you tell if its a gen iv,v,vi

  2. #2
    Member MASTER JOURNEYMAN
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    Nov 2003
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    Just a guess, but I would think the casting no# ? Chevymania has bowtie blocks included in the big block section. Sean
    http://www.chevymania.com/

  3. #3
    Senior Member RACING JUNKIE
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    Just a stupid question maybe...I know what a gen iv and later is...but what was a gen 1 2 and 3? I know the early ones had the groove in the cam but what was before the mark iv?

  4. #4
    Member MASTER JOURNEYMAN
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    Tod74, I got this from a Super chevy article, about I II and III. The rear grooved cams were in Mark IV in 65 ans 66.
    The legend began on the high banks of Daytona in February 1963. A handful of Chevrolets arrived for the Daytona 500 with something "mysterious" under the hood. While Ford and Chrysler expected to compete against Chevrolet's venerable "W" head 409, the Bow-Tie guys had a rather large surprise waiting for them. As Junior Johnson's Chevy thundered around the track at speeds in excess of 160 mph, every soul from the garages, to the pits, to the stands knew that was no W block. Hot on Junior's heels was Johnny Rutherford in another Chevy. The Chevrolets of Ray Fox, Smokey Yunick, and Bubber Farr all ran with power unmatched by the 409, and Ford and Chrysler cried foul. What was this "mystery motor" that Chevrolet was running?

    Inside Chevrolet Engineering, it was called the Mark II, a 427ci V-8 that had no bloodline with the 409, which was dubbed the "Mark I." The word "Mark" was derived from the European tradition of using "Mark" to designate succeeding phases of a design. Instead, it was a totally new design that started in the summer of 1962 when Chevrolet Engineering's Dick Keinath started work on a replacement for the W block. Keinath started with the same bore centers (4.84-inch) as the W block. To keep things differentiated in the minds of Chevy engineers working on both engines, the planned successor to the W block was dubbed "Mark II." It was this big-bore, short-stroke 427 powerhouse that tore up the Daytona high banks.

    The Mark III was a 1963 design study that had features like the Mark II, but had a bigger bore center. None were produced, since it required too much tooling money at the Tonawanda engine plant to change bore centers. The Mark IV went into production in 1965, displacing 396 ci. Mark IVs were subsequently produced in versions of 427 and 454 cid. Deck heights were 9.80 inches

    The cylinder heads were kept under wraps at Daytona in 1963, and all throughout the development process. Less than 50 of these engines had been cast before GM slipped out of racing in January 1963. The large-diameter valves were canted, causing them to stick out at odd angles, which then lead to the engine being nicknamed "Porcupine."

    From 1965 until it was discontinued in 1974, the Mark IV big-block was produced in a variety of horsepower configurations. It served duty in everything from mundane station wagons with trailer packages, to pavement-melting super Chevys that ruled the streets and the drags.

    Even after they were discontinued from production, the Chevy big-block continued on as the GEN II crate motor that powers drag cars, street rods, and the hottest street machines today. Like all great engines, the Chevy big-block will be around to power street machines for generations to come.

  5. #5

    great post

    68bbnova, that was a very good post you made about the mkI, II, III BBC. I have wondered about that also. No much, :lol: but also.

    thanks,
    gyrogearloose

  6. Racing Junk


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