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Living in a cage of fear
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Discussion Starter #1 (Edited)
So... took the Miller out Sunday. Engine runs GREAT!!

Last year, the boat pulled hard, topped at 70MPH at 5200 RPM.

Now, at around 60 MPH , it starts to "rattle" and vibrate, and the engine "revs". I am certain that it is cavitation.
As soon as you let off, it stops and will cruise like a swiss watch right up to 60 or so. There is PLENTY of motor left, just wants to suck air.

When I had the intake reset this winter, I did notice that the "spoon" or lump before the grate on the bottom had been removed.
Is this generally enough to cause cavitation at speed?
The pump mods were a droop and Hyd. place, new detailed A/B. No shoe or plate.

It doesn't matter where I trim it, at 60 MPH it breaks loose.

The boat wants to go, and I am certain it will pull hard far past 70 MPH comparing it to how it ran last year.

So.. Is the removal of the "lump" on the bottom capable of causing this? If so, how should I build it back?

I have had this boat for 3 years, 3 different engines and have NEVER had it cavitate before now.
 

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I could be way off here...but I'd guess your new intake is set at the wrong angle, or you're sucking air through the sides of it. Why else would it have worked o.k before the new intake(reset)????
 

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Living in a cage of fear
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Discussion Starter #3
I could be way off here...but I'd guess your new intake is set at the wrong angle, or you're sucking air through the sides of it. Why else would it have worked o.k before the new intake(reset)????

Thats why I was wondering if the removal of the "lump" during the reset would make a difference?

The intake was not relocated, just pulled and resealed, to my knowledge.

Something ain't right. :|err
 

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Living in a cage of fear
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Discussion Starter #6
Why was the lump removed??
That is a very good question. I did not want it removed. I understand its purpose, and was concerned from the moment I saw it was gone. that could be why i am sort of focusing on that.
 

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Living in a cage of fear
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Discussion Starter #8

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Resident Ford Nut
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Wow Tommy,

That sucks, so who removed the spoon ?

S CP :D
 

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Intake

I would be pissed :|err:|err:|err I would go back to the guy and see WTF was up with the removing the spoon.... and If he has a clue to what he doing, make he redo the bottom or pay to have it redone. You know why it was there "to improve the loading of the pump" If I understand it right.IMO it if the pump could suck air from intake to suction housing it would leak water?:)devil:)devil
 

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Living in a cage of fear
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Discussion Starter #11
Wow Tommy,

That sucks, so who removed the spoon ?

S CP :D
Yeah, it sucks big time.

I busted my ass every day (9 days, 12 hours a day) on my days off to finish the entire boat. re-carpeted, entire replumbing the water system, built all new braided lines, finished the engine and installed it with the new headers, installed the Jet, new place, all controls new, finished up at noon on Sunday and was on the lake at 2:00.
Left for work Monday morning.

Rather not say who did the intake, but wish I had done it myself, or just left it alone.

but what I really need to know is how to go about rebuilding that bump. I will start with that, and am sure it has to be a factor.
Even if you just creep up on the GPS, at 60 it spins its wheels.

I'll get it back, just a little disappointing after all that work and $.
 

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Is this a miller V bottom? Plenty of them around here...dont think any have spoons though...
 

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Miller

I dont know if this will help but when we were looking into purchasing a miller 19, miller boats told us that they changed the bottom design around 78-79. Not positive. Call Miller.
 

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Living in a cage of fear
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Discussion Starter #16 (Edited)
Mine runs Hard (80) with a jacuzzi WJ , no spoon no Bump,same bottom as yours , curious to see some pics Tommy ! Tom

Here are couple after the engine install.



Here is the transom after pulling the old jet.
I wish to God I would have taken some of the bottom. I do know that this boat had the bump, as I remember someone asking a couple years ago about it, and I crawled under it to look and was surprised to see a big lump on the bottom.
At that time I was unaware of spoons on jet boats.


Here it is last year.
 

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Living in a cage of fear
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Discussion Starter #18
Has it still got that same intake loader grate in it as before? My boats have no spoon in the bottom. Recheck intake installed position and angle. Pat

Same grate, same intake. Will be home again in 2 weeks. Will pull out the straight edge and give it a twice over.
 

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Tommy , thanks for the pic/vid , assuming that was last year and the boat is worse now? even the boat ride in the vid appears to be a smidge "wet" to say near the fuel fills ? although mine admittedly has little in it but a motor and seats it runs on about 36" of bottom Still llike to see the intake area and bottom around the intake Tom
 

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Living in a cage of fear
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Discussion Starter #20
Tommy , thanks for the pic/vid , assuming that was last year and the boat is worse now? even the boat ride in the vid appears to be a smidge "wet" to say near the fuel fills ? although mine admittedly has little in it but a motor and seats it runs on about 36" of bottom Still llike to see the intake area and bottom around the intake Tom

It will be a couple weeks before I get home again. I'll get some pics underneath then.

I went with the droop and diverter to try to get it drier, and it seems like it wants to perform much better than in that video, right up until it chatters.

It is WAY snappier, responsive and just basically a bad ass ride... up to 60 MPH.

I imagine I'll have to bring it to one of you experts to get it figured out. I can change parts and work on every thing on it, but have little knowledge of intake mounting angles, or diagnosing things like this, whereas some of you deal with this for a living.:)devil:)devil

I'll try stuff over the summer, and most likely will be bringing the boat to one of the "Big Three" on here towards Fall.:)hand:)hand
 
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