Velvet Drive possible dumb question

Discussion in 'Inboards' started by Bilito, Apr 22, 2010.

  1. Bilito
    Joined: Feb 2010
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    Bilito Junior Member

    Now I am really confused, at least I know what I must do to get my boat going. I have this beautiful newly rebuilt engine sitting on a stand in my garage almost ready to test run, Just gotta change the transmission index and wire it up
     
  2. Jango
    Joined: Aug 2005
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    Jango Senior Enthusiast

    I'm sure the info on indexing the oil pump is right on. You might get lucky, It may already be set to the correct rotation.
     
  3. VDT
    Joined: May 2010
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    VDT New Member

    Almost all engines sold today for marine applications are clockwise rotation when viewed from the front to the engine. Merc, PCM, Indmar, Marine Power, Volvo and almost everyone else gets motors from GM. You can buy reverse rotation motors but they are not standard.

    The 1017000004 is a 1:1 direct drive and will only provide foward propulsion in the same direction as the engine. The reverse gear and clutches are not rated for foward propulsion. The pump on the face of the transmission can be rotated to accomodate reverse rotation motors but fwd is still in the direction of the motor rotation.

    The arrow at the top of the pump casting should be in the direction of motor rotation. Once the bolts are out the pump casting will come out but you don't need to do anything but rotate it. There is a rubber gasket under the pump casting not a paper gasket.

    Hope this helps.
     
  4. apex1

    apex1 Guest

    Sorry, thats not only extremely exaggerated, it is just wrong! GM has a minor share in marine propulsion!

    Regards
    Richard
     
  5. powerabout
    Joined: Nov 2007
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    powerabout Senior Member

    Bilto as mentioned above to stop the confusion the rule of thumb is to look at the flywheel of a marine engine to determine rotation.
    So your std car/truck engine that rotates clockwise from the front is CCW from the rear.
    You can see the confusion when you have a LH and RH engine in a vee drive set up....where is the front??
    Hence th euse of the flywheel as that is where the drive going to be connected.

    Chev make thousands of reverse rotation petrols as every twin shaft rig has/had one due to the fact that the Velvet drive cannot reverse the prop rotation ( 1:1 or any other) so the engine must go the other way to get LH and RH props running.

    Detroits were the only diesels I know that could also be supplied in rev rotation. ( and others I'm sure for tanks and stuff like that)
     
  6. Obsession
    Joined: Jan 2010
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    Obsession Junior Member

    OK, I'm curious. If not GM based blocks, who has the major market share of inboard marine engines installed? Are we calculating market share by number of units or $ ?
     
  7. apex1

    apex1 Guest

    Kubota, Yanmar, Perkins, Cummins, Cat, John Deere are the bigger boys in marine propulsion up to 400kw.
    Above that, MAN, MTU, Wärtsilää play a role.
    And even Deutz has a bigger share in some segments.

    And, of course numbers of installations count, not value.

    Regards
    Richard

    Only when one counts petrol / gas engines as well, GM plays a role. But who does on a worldwide market?
     
  8. Jango
    Joined: Aug 2005
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    Jango Senior Enthusiast

    Since Petrol (gasoline) powered boats represents a signifacant, probably 90%, of the boats in the US and Canada, I would say GM is a very major player since 95+% Inboards, use GM engines. Probably 100,000 + in operation
     
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  9. apex1

    apex1 Guest

    Yeah, US and Canada, (and even there your figures are by far too high), but...

    ....thats not the world (fortunately).
     
  10. sdowney717
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    sdowney717 Senior Member

  11. rrrwel
    Joined: Jan 2010
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    Location: Wisconsin

    rrrwel Junior Member

    I'm looking at a repower also. I have a pair of 454 Crusaders, one is a reverse rotation. My current transmissions ars Velvet drive 72c's. The engines I'm looking at are both standard rotation so it looks like I need to get new transmissions also. I'm looking to see which transmission I should be looking at for ease of installation. Which one will match up without having to perform at lot of modifications the stringers and mounts .

    Thanks
     
  12. Jango
    Joined: Aug 2005
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    Jango Senior Enthusiast

    No problem at all using the 72C,s. Probably the Best Transmissions out there! You just need to align the oil pump for the correct rotation - a 10 - 15 minute job
     
  13. rrrwel
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    rrrwel Junior Member

    I don't think so because then I'll have 2 right hand turning props and I still want to maintain counter rotation at the prop.
     
  14. Jango
    Joined: Aug 2005
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    Jango Senior Enthusiast

    I would consider changing rotation of one of the Engines. i.e. Camshaft, starter and alternator etc
     

  15. mr hot rod
    Joined: Jan 2010
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    Location: Chelsea, Quebec, Canada

    mr hot rod Junior Member

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