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BBC identity question

Discussion in 'The Garage' started by tiger9297, Jul 21, 2006.

  1. tiger9297

    tiger9297 1/2 ton status

    Jul 23, 2004
    Likes Received:
    Tupelo, Mississippi
    How can you tell if a BBC is a 366 or 454, or anything else for that matter, just by looking at the engine?
  2. nvrenuf

    nvrenuf NONE shall pass! Premium Member

    Jan 7, 2002
    Likes Received:
    Mobile, Al.
    There are tall deck (like the 366) and short deck (like the 454) version of big blocks, to tell the difference between the two the tall deck motors usually have 2 thermostats so the water neck looks like a pair of boobies :D .

    As for determining displacement, you'll pretty much have to run the numbers. I do know that some of the later model 454's (mid 80's + ) had "7.4" cast on the middle of the pass side of the block, I don't think the early stuff had this.
  3. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

    Dec 14, 2001
    Likes Received:
    Pleasanton, CA.
    The only BBC that was externally balanced was the 454. If you can see the back of the harmonic balancer there should be a weight cast into the center hub portion of the balancer that goes about half way around the inside diameter of the balancer. If the engine is out of the vehicle the same goes for the flywheel/flexplate. The weight here isn't that big but definately a weight attached to the front (engine) side of the flywheel/flexplate.
  4. diesel4me

    diesel4me 1 ton status Premium Member

    Jul 24, 2003
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    old ones?...

    Older 366 and 427 "tall deck" motors often had a govenor built into the distributor that ran off vacuum too...once you see a few tall deck motors,its readily apparent how much taller the block is under the heads...the dual thermostats is another dead giveaway as already noted,but some 454's had that setup in C-60's and other "big" trucks and busses too..the engine code is the best way to determine exactly what it is..

    The 427 tall deck motor is a keeper,but a 366 is only good for looks,it looks like all other BBC,but it isn't a real powerhouse or torque monster,its built for longevity,not so much for power...kind of a dog as far as performance..:crazy:

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