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Thread: LOOKIN 4 CHEVY SBC 400 ENGINE BUILD TIPS PLEASE

  1. #1
    Senior Member EXPERT BUILDER
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    LOOKIN 4 CHEVY SBC 400 ENGINE BUILD TIPS PLEASE

    HELLO,MY STOCK 400 BLOCK NEEDS TO BE BORED. WAS WONDERIN IF I COULD GET AWAY WITH LIKE A .010" OVERBORE AND COAT MY ORIGINAL PISTONS TO MAKE UP THE DIFFRENCE?SOUNDS LIKE A LONG SHOT BUT I DIDNT KNOW HOW THICK WOULD THE COATINGS PEOPLE PUT ON THE SIDES OF THE PISTONS BE.... :wink:

    IM WILLING TO BET EASIEST WAY IS BORE THE BLOCK AND STUFF OVERSIZED PISTONS IN BUT JUST WONDERING SEEINGS THE 400 ARE THIN WALLED...THX IN ADVANCE

  2. #2
    Senior Member RACING JUNKIE
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    It doesn't work that way.

    You could send the pistons off to the coaters, and then when they come back MIC them and then hone the block out with proper piston wall clearance.

    But, typically coatings are only a couple thousands thick, and you have no means to know how much honing will be required to get the cylinder walls cleaned up.

    Just do it right. Take it to a machine shop and have them dial bore the cylinders and see where they need to be bored to. Then buy pistons and have them finish hone the block to the pistons and be done.

    It'll be cheaper and live longer than half a$$ing it.
    -WJ Birmingham

    OneBadGMC.com

  3. #3
    Senior Member RACING JUNKIE oldandtired's Avatar
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    Sounds like you are trying to save the cost of a set of pistons, but I agree with GMC, do it right the first time. You might not be able to buy inexpensive +.010, but you can get them in +.020 resonably priced.

    Dave
    Dave
    http://www.racingjunk.com/profile/343797
    "All that is necessary for the triumph of evil is for good men to do nothing" Edmund Burke

  4. #4
    Senior Member RACING JUNKIE
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    x 3 with what has been described above.. Thats like sticking a square peg in a round hole. If you make it fit, something is gonna break. And How!!!!!

    If you want to have some fun, destroke your 400 cid rotator with a 3.625 stroke crank using a 4.030 block bore. You have a selection of connecting rod sizes to use; a 5.7, 5.85 or 6.00 rod. This will vary with the disign of your piston.

    If you use the 6.00 rod you can have the piston designed to have the wrist pin slightly dropped keeping it out of the lower ring grove. This positions the piston and the wrist pin in a better location for travel keeping excessive wear off the piston skirt.

    All figures pending above, you will end up with a 387 cid. That puppy will be so much fun on the street and at the track.

    You'll have the best of both worlds larger piston bore and rpm ramping with the smaller stroke..

    That little motor will rev up like a rubber band toy, bring you into your desired power range much faster and keeping the power range up there through your shifting points. You'll shift through those gears like they were going out of style...

    Depending on your car/chassis, suspension and weight, you may find you don't need as much ring gear in the readend as you might think, which will reduce wear and tear on your motor if you are using it for street crusing.

    This may not be an option since you already have your rotator, but if you are able to mix up the combo, I would advise you to look into it....
    "Can't Means You Don't Want To"

    Haven't You Stomped A Ford,,,,,,,,,,,, Lately?

  5. #5
    Senior Member EXPERT BUILDER
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    thx all for advice

    ive always been of the mindset no replacement for displacement,i have a 406 in 1 ton 4x4 truck.with vortec heads and a 262 cam quadjet carb it moves pretty well,so in a monte carlo, slightly bigger heads cam and all of 2000 lbs off the scales the torque will move it along well without having to rev past 6000 rpms

  6. #6
    Junior Member SHOW GUEST
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    Just got my 400sbc back from Greg's Cylinder Heads and Engine Shop.

    Went double my origianl budget, but should be worth it. Here is what I let him do:

    The 400 cu. in. block got the max bore and got stroked. So we are at about 434 cubes now. Filled it with a rolling Eagle assembly, balanced the Crank. Added a lumpy Comp Cam, and popped on a pair of Dart Pro1 Alum Heads, Port matched and polished.

    Edelbrock Air Gap Intake crowned by 830cfm carb built by Nickerson's. And breathing fire through a set of Doug's Ceramic coated long tube Headers.

    It will be installed into my 1976 Impala and mated to the newly built 700R4.

    I'm so excited, I can't sleep.


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