Pullin' my hair out!
+ Reply to Thread
Results 1 to 7 of 7

Thread:
Pullin' my hair out!

  1. #1
    CJRacing
    Join Date
    Apr 2009
    Location
    Long Beach
    Posts
    6

    Exclamation Pullin' my hair out!

    "trying" to piece together my first jet boat. Starting with a 18ft. '75 Gemcraft Southwind. I bought the hull w/ interior only; the owner said it had a 454 that turned a 12JC Berkeley. I bought the same pump that came out of it(12JC), and have been trying for the longest time to fit this 455 in it. I have Harding water logs with up and over transom boom tubes. with the engine as far back as the exhaust will allow, I'm still short of the pump by a solid 3". WTF? I never imagined I could be off this far... With the engine and pump mocked up out of the boat, the rear motor mount will be sitting over the intake flange of the pump body by about 2", does that sound right? My idea of an easy solution would be a longer driveshaft, but i heard that doesn't exsist. My current shaft if 6.75"... Any input you may have can/will determin my boating experience this summer. Thanks

  2. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  3. #2
    Senior Member fleetimus's Avatar
    Join Date
    Dec 2007
    Location
    Colfax, Ca
    Posts
    1,260

    Default

    Pictures will help!!!

  4. #3
    TRG
    TRG is offline
    Senior Member TRG's Avatar
    Join Date
    Dec 2007
    Posts
    5,717

    Default

    not too sure but does the olds and BBC have the same type of mount location, is it on a three point system? my guess would be that you start there first.
    I am no pro, but with the info given?...you might wanna check the differences between Chevy's and olds!

  5. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  6. #4
    CJRacing
    Join Date
    Apr 2009
    Location
    Long Beach
    Posts
    6

    Default

    Quote Originally Posted by toddnjuzz View Post
    not too sure but does the olds and BBC have the same type of mount location, is it on a three point system? my guess would be that you start there first.
    I am no pro, but with the info given?...you might wanna check the differences between Chevy's and olds!
    I'm positive they have different mounting locations, but even so I'm a good 3" further back from the previous holes in the stringers. I don't have any pics that would show my problem, but i'll try to get some tomorrow durring daylight.

  7. #5
    Senior Member Constant840's Avatar
    Join Date
    Dec 2007
    Location
    Yucaipa, Ca
    Posts
    911

    Default

    Sounds like you need a driveline spacer or even an actual driveshaft.
    Any custom driveshaft place should be able to build and balance one to spec.
    Or if you have the tools and skills you can build your own and then have it balanced.

  8. #6
    Senior Member Oldsquirt's Avatar
    Join Date
    Dec 2007
    Location
    NorCal
    Posts
    979

    Default

    Quote Originally Posted by CJRacing View Post
    "trying" to piece together my first jet boat. Starting with a 18ft. '75 Gemcraft Southwind. I bought the hull w/ interior only; the owner said it had a 454 that turned a 12JC Berkeley. I bought the same pump that came out of it(12JC), and have been trying for the longest time to fit this 455 in it. I have Harding water logs with up and over transom boom tubes. with the engine as far back as the exhaust will allow, I'm still short of the pump by a solid 3". WTF? I never imagined I could be off this far... With the engine and pump mocked up out of the boat, the rear motor mount will be sitting over the intake flange of the pump body by about 2", does that sound right? My idea of an easy solution would be a longer driveshaft, but i heard that doesn't exsist. My current shaft if 6.75"... Any input you may have can/will determin my boating experience this summer. Thanks
    Those OT pipes are not universal. You need to have the correct offsets in both height and length. Here's one suppliers pageRewarder OT Pipes For what it's worth, you may not find a combination that works. Not all rear decks leave enough room fot OT Pipes.

    Sounds like you have a short driveline. If it bolts directly to the crank, it is probably designed for a 3-point mount set-up where the bellhousing clamps to the pump. If you have 4-point mounts(front and rear cast plates and mounting feet) you can use a more common set-up of a PTO and separate driveline. That should buy you a couple inches.Rex Marine Drivelines and PTOs.
    Last edited by Oldsquirt; 05-12-2009 at 09:52 PM.

  9. #7
    CJRacing
    Join Date
    Apr 2009
    Location
    Long Beach
    Posts
    6

    Default

    Thanks for the info OldSquirt. I'm flying kinda blind through this whole thing. Used to 4 wheels, and not all of the techniques used on 4 wheels translates to no wheels. ha ha

+ 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


Tags for this Thread

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