All Because of More Air In???
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All Because of More Air In???

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    Super Moderator HammerDown's Avatar
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    Question All Because of More Air In???

    After Spark Arrestor modification...
    Without a doubt the engine's getting a LOT more air >>>> however it appears to now be running lean, seems flat on performance and now has a slight stumble off the line.
    Pulled the plugs and even after no-wake/idle time back to the trailer they look like they cam out of the box
    Jetting up 3 sizes to start .
    <img src=http://www.performanceboats.com/gallery/data/500/medium/06-30-11_1234.jpg border=0 alt= />

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    steelcomp was here
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    Wht exactly did you do the the spark arrestor? More air through the spark arrestor shouldn;t change the air/fuel thorugh the carb...you may have distrubed some of the air signal to the carb causing some issues. My first scoop did this on the dyno...caused a lean condition after testing without. One would think then opposite, but none the less. The thought was ot was disrupting the airsignal and in some way effecting the pressure differential in or around the carb, possibly effecting the air bleeds.

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    Super Moderator HammerDown's Avatar
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    Quote Originally Posted by steelcomp View Post
    Wht exactly did you do the the spark arrestor? More air through the spark arrestor shouldn;t change the air/fuel thorugh the carb...you may have distrubed some of the air signal to the carb causing some issues. My first scoop did this on the dyno...caused a lean condition after testing without. One would think then opposite, but none the less. The thought was ot was disrupting the airsignal and in some way effecting the pressure differential in or around the carb, possibly effecting the air bleeds.
    My Baron SA had several windings in it, it was almost 1/2" thick.
    I took it apart and removed all but two windings from the inside, >>> prior to this up around 5K I could hear the SA trying to suck air, kind of like a whistling sound.
    <img src=http://www.performanceboats.com/gallery/data/500/medium/06-30-11_1234.jpg border=0 alt= />

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    Senior Member STV_Keith's Avatar
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    Spend $300 on a wideband O2 sensor and gauge before you spend a lot more on a mota.
    Keith-


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    Super Moderator HammerDown's Avatar
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    Quote Originally Posted by STV_Keith View Post
    Spend $300 on a wideband O2 sensor and gauge before you spend a lot more on a mota.
    No can do > water injected headers/exhaust.
    <img src=http://www.performanceboats.com/gallery/data/500/medium/06-30-11_1234.jpg border=0 alt= />

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    gn7
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    Quote Originally Posted by HammerDown View Post
    My Baron SA had several windings in it, it was almost 1/2" thick.
    I took it apart and removed all but two windings from the inside, >>> prior to this up around 5K I could hear the SA trying to suck air, kind of like a whistling sound.
    Well duh. You removed the damn choke, and now you wonder why its running lean? Don't make me drive to PA just to slap you around! One of these days we should hold a class on here, on nothing more than the subject of PRESSURE DIFFERENTIAL and why, not how, but WHY, a carb works.



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    Last edited by gn7; 08-02-2010 at 02:51 PM.

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    Super Moderator HammerDown's Avatar
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    Quote Originally Posted by gn7 View Post
    Well duh. You removed the damn choke, and now you wonder why its running lean? Don't make me drive to PA just to slap you around! One of these days we should hold a class on here, on nothing more than the subject of PRESSURE DIFFERENTIAL and why, not how, but WHY, a carb works.
    Damn Bob, you're so sexy when you get worked up

    Guess I couldn't believe just how restrictive the pre modified spark arrester was. Shucks, now it even has a stumble of idle!

    As mentioned prior, jumping up 3 jet sizes to start and hope it gets lively again > and the off idle trip goes away too.

    I better not even ask about the PV GN might come after me with a hatchet!...
    <img src=http://www.performanceboats.com/gallery/data/500/medium/06-30-11_1234.jpg border=0 alt= />

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    cfm
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    Have run into several times where the arrestor caused a too rich condition. Basically, a too restrive arrestors works like a choke door that is restricting air and thus makes the A/F richer.

    Mot notable was a 9" X 4" K&N arrestor on a mild small block. Notable because one would think it would have been fine on that motor.

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    gn7
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    Quote Originally Posted by HammerDown View Post
    Damn Bob, you're so sexy when you get worked up

    Guess I couldn't believe just how restrictive the pre modified spark arrester was. Shucks, now it even has a stumble of idle!

    As mentioned prior, jumping up 3 jet sizes to start and hope it gets lively again > and the off idle trip goes away too.

    I better not even ask about the PV GN might come after me with a hatchet!...
    Here, put one of these on it, and you will be able to take some jet back out.
    http://www.summitracing.com/parts/KNN-85-8913CO/
    And yes, your little mod is definitely going to delay the opening of your PV. But that may be a good thing. Do you have any idea how much I would kill to be able to add 3-4 jets sizes and still be lean. Do you have any idea the power increase.

    Can't say as I blame you for running that thing though. Last thing you would what to do is singe your hair in a backfire





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    Super Moderator HammerDown's Avatar
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    Quote Originally Posted by gn7 View Post
    Here, put one of these on it, and you will be able to take some jet back out.
    http://www.summitracing.com/parts/KNN-85-8913CO/
    And yes, your little mod is definitely going to delay the opening of your PV. But that may be a good thing. Do you have any idea how much I would kill to be able to add 3-4 jets sizes and still be lean. Do you have any idea the power increase.

    Can't say as I blame you for running that thing though. Last thing you would what to do is singe your hair in a backfire

    Oh har-har-har...I'm just trying to get my junk up to GN7 standards > "where overkill is just barely adequate" > and I corrected the spelling
    <img src=http://www.performanceboats.com/gallery/data/500/medium/06-30-11_1234.jpg border=0 alt= />

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    gn7
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    Quote Originally Posted by HammerDown View Post
    Oh har-har-har...I'm just trying to get my my junk up to GN7 standards > "where overkill is just barely adequate" > and I corrected the spelling
    HEY, I didn't write it. I only quoted it. The author is a DRAG racer. And sometimes they don't so good



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