Velvet Drive Question

Discussion in 'DIY Marinizing' started by DOGGYDOO, Aug 8, 2005.

  1. DOGGYDOO
    Joined: Aug 2005
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    DOGGYDOO Junior Member

    Looking To Mate A B/w Velvet Drive To A 455 Olds. Still Sourcing Out The Bellhousing. Question Can I Use A Universal Joint Coupling Like That Comes With A Jetboat Application? Also What Would My 71c 1.52 Ratio Accept As Far As Horsepower Torque? This Engine Is Roughly 350 Horse With 450 Torque. I Do Have A Line On A 72c 1.1 So Thats Why I'm Asking. Dave In Fort Lauderdale
     
  2. PowerTech
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    PowerTech Senior Member

  3. PowerTech
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    PowerTech Senior Member

  4. DOGGYDOO
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    DOGGYDOO Junior Member

    Ok So I Found A Rebuilt B/w 72c But Its 1.1 Ratio. Do I Need A Reduction Box? I Also Found A72c With A1.52 Ratio Box. I Have A Motor Rated At 500 Foot Pounds And Made To Rev 6000. If I Propped It Accordingly Would It Perform Correctly Without Thereduction Box/ My Goal Isto Keep Engine Revs Around 4200 Andobtain 60 Mph. Would This Be Best Obtained In This Setup Or With Thereduction Box And Reving To Say 5500? Dave In Ft. Lauderdale
     
  5. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    Model 71C
    gas HP 310@4200RPM
    Diesel HP 182@3200RPM

    Model 72C
    Gas HP 475@4200RPM
    Diesel HP 274@3200RPM
     
  6. DOGGYDOO
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    DOGGYDOO Junior Member

    Gear Selection

    Ok I'll Go With The 72c. Its 1:1 So How Do I Know If I Should Use A Reduction Gear? The Previous Setup Had A 1.52 Reduction But That Was With A Chevy Straight Six. The Engine I'm Installing Is Basically 400 Hp But 500lb Torque At Around 3000. So Can I Eliminate The Reduction And Prop It Accordingly. My Goal Is To Keep The Engine Revs Under 4500 .. But Also Without The Reduction Gear Wouldn't I Get Better Fuel Mileage? Dave
     
  7. PowerTech
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    PowerTech Senior Member

    you beter go with the 1:1.
     
  8. gonzo
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    gonzo Senior Member

    However, you'll need a bigger prop to absorb the extra HP. One way to do it is to use a 4 or 5 blade prop. It will have more blade area. If you use a bigger diameter prop, then you'll have to use more reduction in the gears. The blade tip speed is what is critical for cavitation- more diameter=more speed.
     
  9. DOGGYDOO
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    DOGGYDOO Junior Member

    shaft log

    ok now you're gonna laugh for sure. i am going to correct this situation, but, this is a boat that had been converted from stern drive,. one of the first things i noticed and why i decided to replace everything was that after i pulled the engine transmission combo it was at this time i noticed that the engine transmision and shaft log were slightly angled to the starboard side i.e. they are not in true dead center straight. this alarmed me. is there any reason someone would do this or is it just sloppy installation? the boat overall ,, which is a formula 23'3 1968 vintage, has been rebuilt restored reconditioned quite nicely prior to my acquisition so this one point was the only thing that looked incorrect.
     
  10. DOGGYDOO
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    DOGGYDOO Junior Member

    btw i am installing a gasket kit in the 72c tonite. having already inspected the 71 c before i must say they look very simalar internally,, so what are the 72c upgrades? more clutch plates i assume . looking for an expert advice on this one. dave in ft. lauderdale
     
  11. gonzo
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    gonzo Senior Member

    The 72C is about 1 1/4" longer and has more clutches.
     
  12. DOGGYDOO
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    DOGGYDOO Junior Member

    Front Pump 72c

    According To The Velvet Drive Maual The Front Pumps Are Interchangeable Between The One That Has The Backing Plate And The One Without. Does Anyone Know The Difference? Also I Examined Both Front Adapter Housings And They Appear To Be Identical Including Similar Part Numbers. Is There Any Internal Differences There Between The 71c And 72c Front Adapter Housing? As I Would Like To Swap My 72c Housing Which Is In Poor Condition To The One That I Removed From My 71c Which Is Much Cleaner And Has A New Needle Bearing. Thanks Dave
     
  13. ENZO
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    Location: veenezuela

    ENZO New Member

    ANYONE CAN GIVEE ME ADVICE. I WANDER IF THERE IS A WAY TO REDUCE GEAR RATE FROM 1.98:1 TO SAY 1.50:1 ON A S-7000 VELVET DRIVE. IF SO WHAT IS THE KIT No. AAND WHERE I CAN PURCHASE IT?

    THANKS

    VINCENZO D'AMICO - CARACAS - VENEZUELA
     

  14. gonzo
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    gonzo Senior Member

    The reduction gear, which is bolted to the back, can be changed. I don't know who is a dealer in Venezuela.
     
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