Effect of changing impeller to stator clearance?
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Effect of changing impeller to stator clearance?

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    Default Effect of changing impeller to stator clearance?

    I've been thinking of putting the bowl from my SD309 in my lathe and taking about .200" off the front surface that mates to the intake housing to tighten up the clearance between the trailing edges of the impeller blades and the leading edges of the stator blades. Anyone ever try this and if so what was the result? All you jet experts chime in a let me know what you think. Thanks.

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    mo balls than $cents$ IMPATIENT 1's Avatar
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    Quote Originally Posted by shakescreek View Post
    I've been thinking of putting the bowl from my SD309 in my lathe and taking about .200" off the front surface that mates to the intake housing to tighten up the clearance between the trailing edges of the impeller blades and the leading edges of the stator blades. Anyone ever try this and if so what was the result? All you jet experts chime in a let me know what you think. Thanks.
    it better to take the bowl into a machine shop and have it properly milled square, you will not get it right on a lathe no matter how hard you try. just alil off and you'll be bending shafts, blowing bowl gaskets.

    its very common to close the gap by taking off the bowl jus not alot of peeps think of checking that gap, which is a big plus for me in this part of the country i leave hardddddd

    Dare to be different, if it turns out great you can claim you planned it that way.

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    Quote Originally Posted by shakescreek View Post
    I've been thinking of putting the bowl from my SD309 in my lathe and taking about .200" off the front surface that mates to the intake housing to tighten up the clearance between the trailing edges of the impeller blades and the leading edges of the stator blades. Anyone ever try this and if so what was the result? All you jet experts chime in a let me know what you think. Thanks.

    I've had it done for me in the past. I wouldn't do it again. I'd make a stuffer that fits correctly instead.

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    Senior Member OkieDave's Avatar
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    Default measure first

    I always move the bowl forward. be sure to measure before you go taking 200 off. might be too much.

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    Quote Originally Posted by shakescreek View Post
    I've been thinking of putting the bowl from my SD309 in my lathe and taking about .200" off the front surface that mates to the intake housing to tighten up the clearance between the trailing edges of the impeller blades and the leading edges of the stator blades. Anyone ever try this and if so what was the result? All you jet experts chime in a let me know what you think. Thanks.
    Shakes does your SD309 has the original AT Impeller with rear stuffer ring ? Tom

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    "Shakes does your SD309 has the original AT Impeller with rear stuffer ring ? Tom" Yes it has the rear ring and shoulder. I have checked it by putting a piece of clay on the rear of the impeller and bolting the bowl up then removing the bowl and measuring the clay. The rear ring does not go into the bowl up to the shoulder. The shoulder is about .240" from the bowl and the rear of the impeller blades clear by quite a bit more so I figured I could safely take off .180" to.200". I am running a 9 1/2" AT impeller(aluminum).

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    Quote Originally Posted by IMPATIENT 1 View Post
    it better to take the bowl into a machine shop and have it properly milled square, you will not get it right on a lathe no matter how hard you try. just alil off and you'll be bending shafts, blowing bowl gaskets.

    its very common to close the gap by taking off the bowl jus not alot of peeps think of checking that gap, which is a big plus for me in this part of the country i leave hardddddd
    Thats funny we bore, face, and turn many bowls in a lathe. Maybe you should change machine shops if they cant dial a bowl in with a four jaw. Im pretty sure thats how most machinists machine bowls. It would be a way bigger hassle to square a bowl in the mill vs the lathe.

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    Yeah if you cant chuck a bowl in a 4 jaw and machine the face dead nuts true with the bore you need to hang up the micrometer. The problem with a mill is how do you know the droop side is square with the front? anyway...

    Now as it does take time I made a expanding arbor that you chuck in the 4 jaw index it true and then slide the bowl on to it, then you expand the arbor and it locks on the bearings. Then the live center goes in the tailstock end of the fixture. So the bowl in held true in all dimentions to the bearing bore. Now you can machine anything you want perfect with the bore...and let me tell ya over the years i've seen some real beauties as far as alignment goes....amazing how screwed up some are. The nice thing is you can also true non droopsnoot bowls as well...really nice for stockers ect.

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    I just recently learned both flanges of the bowl need to be square with each other. For water passage alignment.

    Mill would be the best tool to square them up.
    If For Some Reason I Do Something Worthy Of Recognition. God Provided The Ability And Deserves The Credit.


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    Quote Originally Posted by Infomaniac View Post
    I just recently learned both flanges of the bowl need to be square with each other. For water passage alignment.

    Mill would be the best tool to square them up.
    you must have a shitty machine shop rotflmao

    Dare to be different, if it turns out great you can claim you planned it that way.

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    So I've had some opinions both for and against doing this so far. Can anyone who has done this be a little more precise on exactly what the effect was? A little more boat speed at the same rpm? Did you lose top rpm but keep the same speed? Lose both speed and rpm? My thinking is excess gap would leave more space for the water to tumble in creating turbulence that would waste energy. Closer gap would mean straighter flow and a more efficient pump. Like to hear from those that have done this on their before and after results though before pulling the bowl and cutting it. Thanks for all the opinions so far.

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