downsides of a 400sbc block?
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downsides of a 400sbc block?

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    mo balls than $cents$ IMPATIENT 1's Avatar
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    Default downsides of a 400sbc block?

    guys, are the 400 blocks pretty weak? only thing i can remember about them is the cooling issue, but that's a non issue in a jetboat. what were the other downsides? i've got a nice block, just didn't know if its worth using of if i'm gonna have to make this a 2yr project, buy a lil m block

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    Senior Member H20MOFO's Avatar
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    I'd think the lack of head gasket surface(siameesed cyl walls) would make head gaskets a challenge with a boosted appl.
    Another Hot Boat refugee

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    Cantard 71hallett's Avatar
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    They start splitting at about 650 - 700 hp.
    Quote Originally Posted by gn7 View Post
    It would be a balmy 85* in Steel's shop if he would move a little faster

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    Quote Originally Posted by IMPATIENT 1 View Post
    guys, are the 400 blocks pretty weak? only thing i can remember about them is the cooling issue, but that's a non issue in a jetboat. what were the other downsides? i've got a nice block, just didn't know if its worth using of if i'm gonna have to make this a 2yr project, buy a lil m block
    You put those heads on it that I sent you the link to and you will need a dust pan to pick it up. lol
    Quote Originally Posted by gn7 View Post
    It would be a balmy 85* in Steel's shop if he would move a little faster

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    Quote Originally Posted by H20MOFO View Post
    I'd think the lack of head gasket surface(siameesed cyl walls) would make head gaskets a challenge with a boosted appl.
    one would think that this would be one of the big problems, but evidently it isn't because the rocket and dart blocks are used for high boost, big spray, and big compression, and they have the same bore spacing. it's all in the head gasket you use, and the fact that the block doesn't move around as much.



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    Cantard 71hallett's Avatar
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    Quote Originally Posted by gn7 View Post
    the 4 bolts are pure junk
    You got that right!! Why they built a block with bolts that thread into nothing is beyond me.
    Quote Originally Posted by gn7 View Post
    It would be a balmy 85* in Steel's shop if he would move a little faster

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    Some guy obnoxious001's Avatar
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    Quote Originally Posted by IMPATIENT 1 View Post
    guys, are the 400 blocks pretty weak? only thing i can remember about them is the cooling issue, but that's a non issue in a jetboat. what were the other downsides? i've got a nice block, just didn't know if its worth using of if i'm gonna have to make this a 2yr project, buy a lil m block
    I don't see where you mention forced induction here, maybe I missed something.

    We run 400 blocks in a dirt modified that I build engines for. We had a destroked combination that we were running in a 4 bolt block on race gas, no issues except the bore was a little tired and we went to a 2 bolt block for this year.

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    mo balls than $cents$ IMPATIENT 1's Avatar
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    i've got a 2 bolt, thought i could 4 bolt it with splayed billet caps, maybe get 1000hp outta it with some boost. what is making them split at 700hp?

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    Quote Originally Posted by IMPATIENT 1 View Post
    i've got a 2 bolt, thought i could 4 bolt it with splayed billet caps, maybe get 1000hp outta it with some boost. what is making them split at 700hp?
    Broken mains. Should be able to buy a block for about $1900
    Quote Originally Posted by gn7 View Post
    It would be a balmy 85* in Steel's shop if he would move a little faster

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    mo balls than $cents$ IMPATIENT 1's Avatar
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    Quote Originally Posted by 71hallett View Post
    Broken mains. Should be able to buy a block for about $1900
    found a boat to put it in, he's sending me pics tonite lil 17ft predator, so i'll be buyin the lil m block for this project. this will be my 1st 2yr project, so next summer will be spent on the toon

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    gn7
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    the whole block jumps around, but the biggy is like 71 Hallett says, it will show up as broken mains before anything else



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    thanx for the info guys, looks like i just need to freshen up the 412sbc and put it to the side for a spare i'll buy a lil m block.

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    Default Motown

    Motown Cast Iron Blocks
    At first glance, one of the more noticeable differences between the World Motown and OEM Chevrolet blocks are the “bulges” at each cylinder. That’s because the “Motown” has thicker cylinder walls, and the water jackets have been expanded to provide required cooling. The Motown block can be bored to max of 4.200". DO NOT EXCEED.
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