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Thread: need info

  1. #1
    Hello all,
    I need some info on a bb chevy or maybee a web site. I'm buying a forged lower end and am considering since i'm doing that of stroking the motor. what i need to know are what combinations of bore and stroke equal what CI? and once i settle on a size which is better longer rods with higher pins or shoter rods with lower pins?

  2. #2
    Bore x Bore X Stroke x .7854 x 8 (# of cyl) = Engine size
    Have Fun w/ the calculations! Mike

  3. #3
    Check out this will calculate it for you

  4. #4
    thanks for the info guys i was actually looking more for proven setups like the largest you can go with a stock block. i have been told the largest you can go in a 454 is 496ci? any input?

  5. #5
    Racing Ray
    I have run several 511 cubic inch engines in a stock block. However to bore one out .125 it requires filling the block with Hard Blok to stabilize the cylinders.
    The 496 is .100 over and is the most you would want to go without block filling. That would require a 4.250 crank. I use a .400 long rod with this combo.
    This moves the wrist pin hole into the oil ring groove and requires either a support ring for the oil ring or a filler plug that goes in after the wrist pin.
    You get these when you spec out that rod length and stroke combination. The upside is the piston is very short and VERY light.
    [This message has been edited by Racing Ray (edited April 24, 2002).]

  6. #6
    Boater Bill
    I'm running a 489 BBC which is a 4.28 bore with a 4.25 crank. Rods are also .25 longer @ 6.385. I love it, makes plenty of power with just a single carb in a jet boat.
    Ray - isn't a 496 the same combo above except 60 over (4.31 bore)?
    I stayed at 30 over to save some room for rebuilds down the line.

  7. #7
    Longer rods are better. Allows more "pause" at the top and bottom of the stroke. Better cylinder filling/scavenging.

  8. #8
    Racing Ray
    Yes you are right mine is bored 4.375 X 4.250 = 511.1. It is best to find an early model block as they were cast a bit thicker.

  9. #9
    Actually, a 496 is .060 over with 4.250 stroke. You can use a .070 over piston and get 499, and .100 over is supposed to be safe, at 505 cu in. I ran a 505 for six years with a Gentry turbo set up, 15 lbs boost, close to 1000 hp, with no problems. The engine is sitting in my garage for sale as the boat was sold less engine.

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