crankshaft question
+ Reply to Thread
Results 1 to 7 of 7

Thread:
crankshaft question

  1. #1
    Senior Member
    Join Date
    Jun 2009
    Location
    S.W. PA.
    Posts
    574

    Default crankshaft question

    Im looking at 2 bbc cranks, both are 4inch stroke. One says must use stock rod length the other says must use +.25 rod. This is not a kit ,no rods or pistons involved. What would be the difference in the two cranks to need two different rod lengths? Theres also 50 bucks price difference. What am i missing?

  2. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  3. #2
    Senior Member flat screwd's Avatar
    Join Date
    Oct 2008
    Posts
    279

    Default

    The Diameter of the counter weight.
    Last edited by flat screwd; 12-04-2010 at 08:25 AM.

  4. #3
    Senior Member
    Join Date
    Jun 2009
    Location
    S.W. PA.
    Posts
    574

    Default

    So basically there is one for talldeck to use the longer rod and the other is standard deck height? The weight is listed as the same for both.

  5. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  6. #4
    just a ski boat with bark Carnivalride's Avatar
    Join Date
    Jan 2008
    Location
    Derby, Kansas
    Posts
    2,811

    Default

    Quote Originally Posted by 5sangers View Post
    Im looking at 2 bbc cranks, both are 4inch stroke. One says must use stock rod length the other says must use +.25 rod. This is not a kit ,no rods or pistons involved. What would be the difference in the two cranks to need two different rod lengths? Theres also 50 bucks price difference. What am i missing?
    Most likely the bobweights are different, typically a longer rod means lighter pistons. I'm just guessing and I didn't look this but a stock replacement deal probably has a bobweight of around 2500gms where the one for the +.250" rods is probably around 2300gms. The only issue is if your bobweight is heavier than the crank you bought the machine shop will have to add heavy metal to balance and that cost more.
    Quote Originally Posted by gn7 View Post
    Carnivalride, you really need to find some other hobby. You have no talent for this boat thing

  7. #5
    Senior Member
    Join Date
    Jun 2009
    Location
    S.W. PA.
    Posts
    574

    Default

    Thanks for the replies. The way the specs were worded just threw me off and i guess i should have thought it through the whole way. thanks

  8. #6
    gn7
    gn7 is offline
    Senior Member gn7's Avatar
    Join Date
    Jan 2008
    Posts
    25,975

    Default

    Quote Originally Posted by Carnivalride View Post
    Most likely the bobweights are different, typically a longer rod means lighter pistons. I'm just guessing and I didn't look this but a stock replacement deal probably has a bobweight of around 2500gms where the one for the +.250" rods is probably around 2300gms. The only issue is if your bobweight is heavier than the crank you bought the machine shop will have to add heavy metal to balance and that cost more.
    Not exactly Carnalride. The REQUIREMENT for the longer rod is due to a larger diameter counter weight like Flat Screwed said. The reason for the larger counter weight is not due to a lighter or heavier piston, its so you can internally balance the crank without mallory metal. It also allows the manufacture to remove the big ass pork chop on the flywheel flange, that really act like nothing more than an external weight. If you don't run .250 longer rods, the piston will crash into the counterweights.



    100% free webcam site! | Awesome chicks and it is absolutely free! | Watch free live sex cam - easy as 1-2-3

  9. #7
    [email protected]
    Join Date
    Feb 2008
    Location
    Ohio
    Posts
    1,011

    Default

    When I got my Callies Comp Star, I was told to get the one that required the longer rod and it could be balanced internally with out metal. And it doesn't have a pork chop on the crank flange.

    Tim

+ Reply to Thread

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Please select your insurance company (Optional)

Log-in

Digg This Thread

Posting Permissions

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
  •  
 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95