High speed air bleed ?
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High speed air bleed ?

  1. #1
    IBEW Local 569 Blown Income's Avatar
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    Default High speed air bleed ?

    When I did the boost reference set-up to my 850s I drilled out the stock push in air bleeds and replaced them with screw-in ones and used the #24 like I had read about. My problem is that I was running the blower 6% over and want to go up to 12%, but I already have 98s in the secondaries. It's got 93s in the primaries with 4.5 high flow power valves. This set-up makes it very driveable and helped the gas mileage considerably. My question is which way is richer on the air bleeds, (I would think that smaller would be) and how much of a difference would the change make?

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    Senior Member slow67's Avatar
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    If your part throttle cruise is not lean after you up the boost, I would drill out the PVCRs.

    A smaller HSAB would richen it on the top end.
    Last edited by slow67; 06-10-2008 at 08:40 PM.

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    IBEW Local 569 Blown Income's Avatar
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    Pvcr????

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    Senior Member slow67's Avatar
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    Quote Originally Posted by Blown Income View Post
    Pvcr????
    Power Valve Channel Restrictor. It is the 2 little passages (1 for each main well) when you pull out the Power Valve. If you need a ton of fuel, you may need to run PVs in the primaries and secondaries. The bigger you go, the more fuel it adds when the PV opens.


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    93/98 jets with .024 HS bleeds in an 4150/850 should be plenty rich (unless the the PV's are staying closed due to blower operation), especialy with a stock type metering block that doesn't have alot of bleed in the imulsion well to begin with (slow67's photo).
    Bleeds can have a big effect on AFR (smaller=richer, larger=leaner) but will also effect the fuel curve throughout the rpm range. Larger bleeds and larger jets tend to tilt the fuel curve from Rich to lean, smaller jets and smaller bleeds tilt the curve more towards lean to rich through the rpm range.

  8. #6
    IBEW Local 569 Blown Income's Avatar
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    Thanks for the info guys. I think I'll fatten the secondaries and try to find some smaller air bleeds and see what happens before I drill out the metering block. It's in the Texas Tunnel and the last thing I want is to have it quit on me at speed you know how these things have a reputation to hook. Fat and Happy and work back from there. All the info is greatly appreciated.
    Last edited by Blown Income; 06-11-2008 at 06:18 PM.

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    Still needs more main jet

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