What would you do with this junk? 557 bbc options?
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What would you do with this junk? 557 bbc options?

  1. #1
    Senior Member H20MOFO's Avatar
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    Default What would you do with this junk? 557 bbc options?

    I think it's time to throw some pistons at my motor in an attempt to bring the compression ratio above that of my lawn mower...
    Question #1, is a 6.135 rod length the only option for a 9.8 deck tall block with a 4.375 stroke?? I'd like to get a better rod angle/ratio.
    #2, with flat tops, what would my compression ratio be with 117cc chambers(prox). And is there a better piston choice for a 91 octane motor?
    Q#3, are brodix bb2plus heads too small for my 557" bbc "under 6k motor"? (112cc runners)

    #4 I'm at an altitude disadvantage(4500ft)...doesn't that mean a higher CR is in order?, and what does that do to head selection(size)??
    thanks for your input....
    Another Hot Boat refugee

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    Senior Member ap67et10's Avatar
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    Quote Originally Posted by H20MOFO View Post
    I think it's time to throw some pistons at my motor in an attempt to bring the compression ratio above that of my lawn mower...
    Question #1, is a 6.135 rod length the only option for a 9.8 deck tall block with a 4.375 stroke?? I'd like to get a better rod angle/ratio.
    #2, with flat tops, what would my compression ratio be with 117cc chambers(prox). And is there a better piston choice for a 91 octane motor?
    Q#3, are brodix bb2plus heads too small for my 557" bbc "under 6k motor"? (112cc runners)

    #4 I'm at an altitude disadvantage(4500ft)...doesn't that mean a higher CR is in order?, and what does that do to head selection(size)??
    thanks for your input....

    Save up a little extra and toss on a blower. That's the real solution for the lack of air...get something that forces it in. I know...not much help.

    AP

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    21 Daytona Outlaw's Avatar
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    Quote Originally Posted by ap67et10 View Post
    Save up a little extra and toss on a blower. That's the real solution for the lack of air...get something that forces it in. I know...not much help.

    AP
    X2
    #55

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    Senior Member H20MOFO's Avatar
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    When I put this together it had some boost planned for the future....
    I'm not certain what direction I'm going to go, but I'm leaning tword simple.
    This is a "family" boat, not looking for huge #'s, just all I can get with pump gas with what I've got.
    Heck it runs 70 with an 8.4 CR, I'd be happy with 80.... plus spray
    If I had to pick one question..... is the 6.135 my only rod choice?
    Another Hot Boat refugee

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    i'm back!! 1QuickCP's Avatar
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    you could go 6.250... lets see u can get flat tops in 1.245 and 1.270 compression height so with 9.8 deck and 4.375 stroke you can use a 6.350 rod..with the 1,25 piston

    About 9.5-1 with flat top and 117cc

    problem is u pretty much need a custom rod to get this length..cause 6.385 is not gunna work

    I dont like a 6.135 with that 4.375 stroke...IMHO just 2 much stroke for a short deck block

    best bet may be 6.385 rod with custom flat top with 1.200 ch thats tight but would work..not the best but not many options
    Last edited by 1QuickCP; 09-29-2009 at 08:20 PM.

  8. #6
    Resident Ford Nut Sleeper CP's Avatar
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    Quote Originally Posted by ap67et10 View Post
    Save up a little extra and toss on a blower. That's the real solution for the lack of air...get something that forces it in. I know...not much help.

    AP
    Blowers are for people who need a crutch

    Get a set of good heads.

    S CP

    "Dark Sarcasm"
    Going fast is only half the fun ... what you make go
    fast is the other half.
    " A Government big enough to give you everything you want is big enough to take away everything you have"

  9. #7
    Senior Member ap67et10's Avatar
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    Quote Originally Posted by Sleeper CP View Post
    Blowers are for people who need a crutch

    Get a set of good heads.

    S CP


    DANG IT!!! Man i wish i would have known this before i bought the blower!!!! I could have built a N/A Big Block Ford otherwise!


    AP

  10. #8
    Senior Member raysoninoz's Avatar
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    Quote Originally Posted by H20MOFO View Post
    I think it's time to throw some pistons at my motor in an attempt to bring the compression ratio above that of my lawn mower...
    Question #1, is a 6.135 rod length the only option for a 9.8 deck tall block with a 4.375 stroke?? I'd like to get a better rod angle/ratio.
    #2, with flat tops, what would my compression ratio be with 117cc chambers(prox). And is there a better piston choice for a 91 octane motor?
    Q#3, are brodix bb2plus heads too small for my 557" bbc "under 6k motor"? (112cc runners)

    #4 I'm at an altitude disadvantage(4500ft)...doesn't that mean a higher CR is in order?, and what does that do to head selection(size)??
    thanks for your input....
    BB2plus have an intake port of 312cc, chambers are 119cc, they appear to suit compression from about 12 & suit a roller cam. If you only want to rev it to 6k these may be ok particularly with the smaller 312cc intake runners. my02c
    Mediocrity is NOT an option...


  11. #9
    Some guy obnoxious001's Avatar
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    Quote Originally Posted by H20MOFO View Post
    Heck it runs 70 with an 8.4 CR,
    Kreg

    Where did you come up with the 8.4-1 compression ratio? Shouldn't it calculate out to more like 9.5-1 with 117 cc chambers?

    What's this about the 9.8" block,, you were working with a bowtie talldeck?

  12. #10
    Cantard 71hallett's Avatar
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    Its a 10.2 deck my boy!!!
    Quote Originally Posted by gn7 View Post
    It would be a balmy 85* in Steel's shop if he would move a little faster

  13. #11
    Cantard 71hallett's Avatar
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    Quote Originally Posted by Sleeper CP View Post
    Blowers are for people who need a crutch



    S CP
    Or the odd saturday night when your down in the dumps cause you just got wooped by a cheby.
    Quote Originally Posted by gn7 View Post
    It would be a balmy 85* in Steel's shop if he would move a little faster

  14. #12
    i'm back!! 1QuickCP's Avatar
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    haha....get ur data correct...10.200 ur now in good shape for rods..

  15. #13
    Cantard 71hallett's Avatar
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    Quote Originally Posted by 1QuickCP View Post
    haha....get ur data correct...10.200 ur now in good shape for rods..
    ....story of his life....half inch to short.
    Quote Originally Posted by gn7 View Post
    It would be a balmy 85* in Steel's shop if he would move a little faster

  16. #14
    i'm back!! 1QuickCP's Avatar
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    Quote Originally Posted by 71hallett View Post
    ....story of his life....half inch to short.
    bawaaaaaaaaa......

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