Why not Level the Engine...?
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Why not Level the Engine...?

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    Super Moderator HammerDown's Avatar
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    Question Why not Level the Engine...?

    Every Jet Engine I see (even mine) is nose up to some degree in the boat why? Now I'm not only talking the jets with a solid drive shaft but also the ones like mine that use a big H-coupler and double u-joint.
    What I'm getting at is this, I'm about to pull my engine and maybe go with a 4-point or a rail mount vs the 3-point I've been using.
    If I have the oil pan/hull clearance why shouldn't I drop the nose or raise the rear to level off the engine?
    Of course the the H-bar and double u-joints can't look like the letter Z but they do need some deflection to work properly...no?
    <img src=http://www.performanceboats.com/gallery/data/500/medium/06-30-11_1234.jpg border=0 alt= />

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    Large Member Watch Me Squirt's Avatar
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    IIRC, it's directly related to the angle of the pump shaft. You want to keep the angle of the crankshaft & the angle of the pump shaft the same. I'm sure the experts will chime in shortly & we'll all be better informed.

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    Senior Member GT Jets's Avatar
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    Quote Originally Posted by HammerDown View Post
    Every Jet Engine I see (even mine) is nose up to some degree in the boat why? Now I'm not only talking the jets with a solid drive shaft but also the ones like mine that use a bid H-coupler and double u-joint.
    What I'm getting at is this, I'm about to pull my engine and maybe go with a 4-point or a rail mount vs the 3-point I've been using.
    If I have the oil pan/hull clearance why shouldn't I drop the nose or raise the rear to level off the engine?
    Of course the the H-bar and double u-joints can't look like the letter Z but they do need some deflection to work properly...no?

    The line of rotation needs to be as straight as possible, there are several easons for this, the largest reason is the straighter the shaft angle the less horsepower it will absorb, the other reasons are vibration and wear and tear on the input shaft of the pump, the driveshaft will "fight" to be straight, so something has to take the torque, which would be the crankshaft and the input shaft....

    One way you could, if you really wanted to level the engine would be to build a constant velocity driveshaft (with double joints and a velocity ball), this would put the torque through the middle of the shaft and you could get pretty extreme with the angles...But a huge waste of effort IMO...

    GT
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    Put a 300 on the back of it, Flywheel it and a nosecone. $15,000 later you'll have a 65 mph pile of shit......

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    true you do need a tiny bit of deflection, the pump sits at 4 degrees and the motor should be very close but just a portion of a degree off so the driveshaft lubes ok, i went through all this with Josh and Tom at JBP this summer and i actually found the blueprints from Berkeley for installing the motor and jet, which shows the 4 degree angle

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    Super Moderator HammerDown's Avatar
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    Crude Paint Shop drawing but from the feedback the top drawing would be how the pump shaft should line up with the crank shaft...correct?
    The center (red) would be my H-coupler w/a large u-joint on either side.
    <img src=http://www.performanceboats.com/gallery/data/500/medium/06-30-11_1234.jpg border=0 alt= />

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    Senior Member H20MOFO's Avatar
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    Good thread Hammar. I heard too straight was bad also, is yours 4* or less? I bought a 5* wedge for my carb(under) it leveled it right out,fwiw.
    Another Hot Boat refugee

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    Super Moderator HammerDown's Avatar
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    Quote Originally Posted by H20MOFO View Post
    Good thread Hammar. I heard too straight was bad also, is yours 4* or less? I bought a 5* wedge for my carb(under) it leveled it right out,fwiw.
    4-5 degree Intake...heck I don't remember, and I set the suction housing
    I'll have my engine out next weekend maybe some numbers on the suction housing/intake will bring back memories.
    Not so much the "carb" sitting level but my thoughts are the whole engine is tilting up, obviously the oil pan too with oil deeper in the rear of the pan and closer to the crank!
    <img src=http://www.performanceboats.com/gallery/data/500/medium/06-30-11_1234.jpg border=0 alt= />

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    Senior Member H20MOFO's Avatar
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    Just don't accelerate and you'll be o.k. lol does yours lean worse than that??
    Another Hot Boat refugee

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    Super Moderator HammerDown's Avatar
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    Quote Originally Posted by H20MOFO View Post
    Just don't accelerate and you'll be o.k. lol does yours lean worse than that??
    Hmmm I don't think mine angles up quite (that) much...I'll have to dig through some pictures.
    Wish this vid was closer...
    <img src=http://www.performanceboats.com/gallery/data/500/medium/06-30-11_1234.jpg border=0 alt= />

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    Senior Member superdave013's Avatar
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    Quote Originally Posted by HammerDown View Post
    Crude Paint Shop drawing but from the feedback the top drawing would be how the pump shaft should line up with the crank shaft...correct?
    The center (red) would be my H-coupler w/a large u-joint on either side.
    you don't want that bottom view.

    Even if its offset like in a lifted truck you still want them to be as parallel as you can get. So you could sink your engine down lower in the boat but to keep the angles right it will still be nose up. Some circle boats do this to lower the C.G.
    I would think in a perfect world using u joints you want the crank and pump shaft to be parallel with each other with just enough offset so the needle bearrings will rotate (like 1 ~ 3 degrees).

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    Super Moderator HammerDown's Avatar
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    Quote Originally Posted by superdave013 View Post
    you don't want that bottom view.

    Even if its offset like in a lifted truck you still want them to be as parallel as you can get. So you could sink your engine down lower in the boat but to keep the angles right it will still be nose up.../
    "sink the engine down" would be Parrallel but (not) inline...correct? My single H-coupler won't allow this.
    <img src=http://www.performanceboats.com/gallery/data/500/medium/06-30-11_1234.jpg border=0 alt= />

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    Senior Member superdave013's Avatar
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    Quote Originally Posted by HammerDown View Post
    "sink the engine down" would be Parrallel but (not) inline...correct? My single H-coupler won't allow this.

    correct, and that's why you should leave it like it is.

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    Senior Member H20MOFO's Avatar
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    How can you compare a truck dl to a jet, when a truck dl has u-joints at each end, and the jet dl has the u-joints in the center? Unless you're talking about the front, and then the cv/ jet style would only be on one end and a reg u-joint would be on the other right? Damn I need more beer.lol
    Another Hot Boat refugee

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