Block choice
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Block choice

  1. #1
    Senior Member River Dad's Avatar
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    Default Block choice

    What are your choices for a block? The project will be for a 19' jet boat primarily used for the river, but will see time at the track as well. Would like to run 10.0 and stay on pump gas. Looking at a 540 aluminum head roller motor and we want to start with a new block.

    What are your thoughts? Dart, Merlin? I'd really like to try and get the owner to step up to an aluminum block, but I'm not sure if that's in the cards. As usual, price is important, but not everything.

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  3. #2
    TEN THIRTY ONE RCB19's Avatar
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    Dart makes a nice product. I've seen a few out of the box nightmares with the Merlin stuff.
    RCB

  4. #3
    Senior Member alkyexpress's Avatar
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    Quote Originally Posted by RCB19 View Post
    Dart makes a nice product. I've seen a few out of the box nightmares with the Merlin stuff.
    X2..... I have had good luck with a Dart (Iron 496 ),Blown alky Hydro.........Eric

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  6. #4
    Senior Member CNC BLOCKS's Avatar
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    Quote Originally Posted by RCB19 View Post
    Dart makes a nice product. I've seen a few out of the box nightmares with the Merlin stuff.
    X2 as we have seen to many problems with the World stuff

  7. #5
    Senior Member cyclone's Avatar
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    Brodix aluminum is fairly cheap and good.

  8. #6
    Red Blooded American The Doctor's Avatar
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    For a cast iron block the Dart "Big M" is our first choice!

    http://www.hotrod.com/howto/113_0206.../photo_02.html
    The best things in life aren't things!

  9. #7
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    Quote Originally Posted by The Doctor View Post
    For a cast iron block the Dart "Big M" is our first choice!

    http://www.hotrod.com/howto/113_0206.../photo_02.html

    X3....World stuff is 4 the birds.

  10. #8
    Senior Member hotbo's Avatar
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    Quote Originally Posted by cyclone View Post
    Brodix aluminum is fairly cheap and good.
    X2 i think Brodix gets overlooked to many times on there products

  11. #9
    Village Idiot fc-Pilot's Avatar
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    The Dart is a good all around block. Do not assume that just because it says Dart it is ready to run. I have had to straiten out the decks on the last three I have got. The last five all needed the mains fixed since they were way out of whack and you have to check the threads on every bolt and plug hole. None of the oil gallery plugs were tapped deep enough. Now don't expect any of the other blocks to be much better. The last CNC Bowtie blocks I got were a little better, but I have not got one of them in a while. I know the Merlin's were "hit and miss" over the last few years but I guess they went to a new foundry recently. It would be nice to see them putting out a great product again like they had with the Merlin Pro blocks.

    Moral of the story, expect to pay more since there will be machining you did not expect. I have no experience with the aluminum blocks so I can't say what they are like.

    Paul

  12. #10
    Senior Member CNC BLOCKS's Avatar
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    Here is what we do to a Big-M block when we machine them
    I deck all of them to a finished number depending on gasket & desired piston height
    Block needs to be honed with a plate or bored & honed depending on bore
    Bottoms of bores need to be chamfered
    Most need the lifter bores honed, at the least checked
    Most need line honing
    All pipe threads need to be retapped
    Oil return from fuel pump cavity needs to be done
    Core plug holes need deburiing
    CHECK THAT THE DISTRIBUTOR GEAR DOES NOT CONTACT THE BLOCK BY THE CAM. There is a big cast blob down there you may want to relieve.

  13. #11
    Senior Member stix818's Avatar
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    Quote Originally Posted by cyclone View Post
    Brodix aluminum is fairly cheap and good.
    Have you seen problems with rings sealing because of cylinders moving around?
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  14. #12
    Senior Member Ahsumtoy's Avatar
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    Aluminum Dart...

    Click image for larger version. 

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  15. #13
    Senior Member cyclone's Avatar
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    Quote Originally Posted by stix818 View Post
    Have you seen problems with rings sealing because of cylinders moving around?
    not really and mine is at 4.600..
    have talked to guys running big n20 hits with bores larger than that and they are claiming not to have problems.

    the only extra machine work mine needed right from the get-go was on the mains. they were .003 undersized.

    other than that, i've been totally happy with my block.

  16. #14
    Gone
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    Ummm.....prolly left out a zero. .0003 ??

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