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Topic: Prop Shaft, Prop Shaft

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Beautiful Noise Male

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Posted: June 11 2007,11:28 am

Post # 1

Art,What is the purpose of cutting the prop shaft to get more lift?
Also can you put the piece's back in?The owner before me had cut about a 1" out in two 1/2" piece's that I have, I'm wondering if it is safe to put them back in to see what it would do to the Boat.
Thanks

Steve
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GoFastRacer Male

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Posted: June 12 2007,7:19 am

Post # 2

Steve, moving the prop back lifts the tail and moving it forward lifts the nose!. Now I see two reasons why he would have cut an inch off, first he was probably driving the nose over at speed, second the prop would have been to far back from the strut and it's hard on strut bushings, the prop should just be far back enough from the strut to get the puller on. If you're not having any handling problems now, moving back that far will give you problems for sure, also if you move it back an inch you will have an inch less keyway engagement which won't leave much at all depending on the lenght of the coupler!. Unless you're having handling problems, I wouldn't mess with it!. Seems to me the last time I saw it run it looked good!.. :stupid

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Beautiful Noise Male

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Posted: June 12 2007,12:11 pm

Post # 3

Thanks ART for the reply...................I can't get off the down Pedal it just wants to lift to bad, maybe its the Plate. I'll take a straight edge to the Plate and see were it's at and get back to You.
Thanks

Steve
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Posted: June 12 2007,9:55 pm

Post # 4

You're welcome anytime Steve!.... So you're saying it won't take a set then, ok that could mean the prop is too far forward, but how long are the plates from the transom??, they are an extention of the bottom and can be a factor??, also what is the distance from the end of the strut to the transom???..

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Beautiful Noise Male

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Posted: June 12 2007,11:57 pm

Post # 5

Art,It feels like when I come off the pedal it just wants to keep lifting............When I take a straight edge to the back the plate is about 3/8"- 1/2" above the straight edge at the very back. I'll get those other answers for you tomorrow....Thanks

Steve
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Posted: June 13 2007,5:56 am

Post # 6

Well that's not right, at a point the boat should settle down and you should be able to get off the plate. If your bottom is like any other B boat with a rocker, the normal setting is 1/8, 5/8 1/4 from left to right, of course if you don't have a rocker it would be a lot less!..

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Beautiful Noise Male

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Posted: June 13 2007,5:47 pm

Post # 7

Quote (GoFastRacer @ June 12 2007,9:55 pm)

how long are the plates from the transom??, they are an extention of the bottom and can be a factor??, also what is the distance from the end of the strut to the transom??

Art,Here goes....The Plates are 10" from the transom also 2 measurments not knowing which one you need ...from the strut (where it comes though the hull) is 24" ....where the Prop shaft comes though the Strut is 20" .....also I have about 1/2" of prop shaft between the strut and the prop for the puller and thats with 1 of the 3/8" pieces of the shaft in which I have always had in.
Rocker?? explain please Ã‚Â

I've heard it but I couldn't tell you if I had it or not :stupid

.What are you doing Tomorrow? could you drive over and take a look :good

Thanks

Edited by Beautiful Noise on June 13 2007,5:48 pm

Steve
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Posted: June 14 2007,5:58 am

Post # 8

Oops sorry, should have been more specific, the strut measurment is from the end of the tube to the transom, and if that is 20" that is right, and if all you have is a 1/2" clearance between the prop that's right also. But your plates are to long for the power you have, if you had a blown motor in there you more than likely wouldn't have that problem of lifting all the time!. One thing you could do is try a prop with a cup on it, that lifts the tail some. I put one on mine last year and it really freed up the boat, got almost 10mph out of it!..

If you lay a straight edge beside the strut, from behind the strut you should se a gradual curve going up as you look back towards the transom, that would be the rocker!... Oh btw, I'll be over in a minute!..

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Beautiful Noise Male

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Posted: June 14 2007,11:12 am

Post # 9

Art,The original owner ran a bigger more horsepower motor than what I'm running he use to run NJBA with it in the 105-110 bracket.Now nothing has been done with the plates since I've owned it Im just thinking that it has way to much lift for my horsepower to drive it down also it does seem like the backend wants to lift also.I'm going to try and hook up with Dave Sammons he and his family come down to Castle Rock on vacations.My other prop had a cup in it BUT last summer I switched over to the Cary Prop which I got from my Buddy that had the Sister Boat to mine with the same set up.
Thanks... oh by the way It's after 11am and your not here yet so I'm going to pour out the Coffee I had made for you :rotflmao

Steve
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Posted: June 14 2007,9:12 pm

Post # 10

Yep thought so, he had the power so you should just up the power a bit and put that prop with the cup back on, that or you're going to have to shorten the plates, mine were 7 1/2"...

Ok so the coffee is gone, time to break out the beer!..

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Beautiful Noise Male

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Posted: June 15 2007,8:43 am

Post # 11

Art,So more power longer plates less power shorter plates?Now how does gearing affect this OR does it? As far as making more power it might be cheaper to shorten the plates if that would do the trick BUT it will have to wait till the summers over and find somebody that knows what thier doing to help

Thanks................Oh by the way the coffee was for you yesterday I dont drink the stuff and trust me the Beer was already broken out :beer

Steve
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Posted: June 15 2007,9:06 pm

Post # 12

Yes, if you notice K boats have longer plates than SS boats!.. A lower gear would help if you're over geared now, what rpm are you are you turning???, remember if the power, gear and prop combo is not right then any other modifications is a crap shoot!.. Now shortening the plates is really an easy task, just cut the forward part off and use it for a template to drill and countersink the new holes, then bolt them back on!.....

Well I don't drink the $hit either, LOL, but you broke out the beer without me, now that is cold!.. :beat

Ã‚Â

Edited by GoFastRacer on June 15 2007,9:06 pm

| Member # 101 | Joined: 3-03-2003 |

Beautiful Noise Male

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Posted: June 15 2007,10:40 pm

Post # 13

Art I'm guessing i'm making somewhere around 550-600 hp I'm running 15 gears and a 11 1/4 X 15 prop & 6800rpm.
Thanks
And yes the Beer was real Cold :beer

Steve
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Posted: June 16 2007,6:00 am

Post # 14

Well, you're a little shy on rpm's there about 700, but I'm questioning the power a bit???, I ran the same prop on mine but with 18 gears and I pulled 6500, and with 15's that would take it up to 6800, so to me that would put the power about the same as mine, and that POS 468 I have now don't come close to 500. Now my 440 had 500-510hp and I pulled 7500 with the 18's, and I was off the plate fairly quick but with this motor pulling 6500 I couldn't quite get off the plate, and I have 7 1/2" plates!. I think I would up the power a bit and put that prop with the cup back on and try it before I went to the trouble of cutting the plates??.. Just my .02!..

Yeah, beer was cold here too!.. :bebe

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Beautiful Noise Male

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Posted: June 16 2007,7:37 am

Post # 15

Art,So you think I'm under powered? My motor is a 468...alittle over 10 1/2-1 ,TRW....World Merlin 320 Rect Port Heads....630 lift cam, Isky Z89.....running 2-750's with a Vertex Mag
Thanks

Steve
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I might not be FAST,But I sure am SLOW

| Member # 70 | Joined: 1-11-2003 |

GoFastRacer Male

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Posted: June 16 2007,7:54 am

Post # 16

Steve, the difference between yours and mine are the heads and my cam is a bit bigger, but my compresion is low too. With those heads you need more cam to make use of the heads and induction, put a roller in there and it will be night and day!.. :good

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Beautiful Noise Male

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Posted: June 17 2007,1:38 am

Post # 17

Art.......................Ok if I was to go with a Roller Cam which one would you recommend? Also what about clearence with the Valve to Piston if I go bigger with the Cam? I doubt with summer getting ready to start for me that it will happen at this time I will probably be waiting till winter to make the change if thats the way I go

Thanks

Steve
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I might not be FAST,But I sure am SLOW

| Member # 70 | Joined: 1-11-2003 |

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Posted: June 17 2007,8:51 am

Post # 18

Well, I'm not sure what I'd use with the compression you have, I'd have to reserch that a bit but you should have plenty of room I would think!.. You might want to talk to Chris (cstraub69) on HB that's all he does is design camshafts, he'd be the one to come up with a good profile for your application!.. :good

| Member # 101 | Joined: 3-03-2003 |

Beautiful Noise Male

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Posted: June 17 2007,10:01 am

Post # 19

Art..Thanks for all the helpful information Ã‚Â :good

BUT it seems like in the long run I need to shorten my Plates for the amount power that I'll end up making since this is not going to be a real high horsepower set up :stupid

when I'm ready for the Cam change I'll check with Chris..I just guess I'll chock this up to the true meaning of owning a BOAT(Break Out Another Thousand) :drink

Ã‚Â

Hey are you and the Wife going to make it out to Parker at all this summer?

Edited by Beautiful Noise on June 17 2007,10:07 am

Steve
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I might not be FAST,But I sure am SLOW

| Member # 70 | Joined: 1-11-2003 |

GoFastRacer Male

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Posted: June 17 2007,8:47 pm

Post # 20

Well, if you're content with the speeds now and not contemplating stepping up to a blown deal later, then I think with a cam change and cutting the plates down a bit that should cure it and you'll have a real nice ride!... :good

Well, if I can find some ole cheap ski boat we may just go out there, it's been a while and it might be fun again!.. :good

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19 replies since June 11 2007,11:28 am

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