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Thread: Holley 4150 Street HP 650 cfm rich at WOT.

  1. #1

    Angry Holley 4150 Street HP 650 cfm rich at WOT.

    Hey guys! I just installed a new Holley 4150 street HP 650 cfm and here's the issue, while I'm cruising I have a good throttle response and my AFR is at 13.5-14. When I go WOT it goes stupid rich! Like 10 to 11 AFR and the engine have lack of power. I lowered the rear jets at #69 and there's no difference. Still way to rich at WOT. So I checked the power valve and I put the 4.5 one and doesnt change anything. Total ignition timing is set at 34° BTDC. I suspect the PVCR are too big, but I want some advice if anybody had this kind of experience with a similar issues!
    Heres my engine specs:
    1990 Ford 5.0L HO
    Trick Flow 170 heads
    Ford Racing E303 cam
    Comp Cam roller rockers
    Ford Racing "Victor JR" intake manifold 9.1 compression ratio
    BBK longtube headers
    MSD 6AL with Pro Billet distributor

  2. #2
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    First thing to check is the high speed air bleeds are clear. Blow some carb cleaner through them. Does it blow black smoke when this stupid rich occurs? Gary
    Regards, Gary

  3. #3

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    Hi Gary! Yes, I got black smoke from the exhaust, the carb is brand new from the box a week ago.

  4. #4
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    Do you have another carb you can try for a test?
    Regards, Gary

  5. #5

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    No, I don't have another one.

  6. #6

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    Float level in the rear set correctly?

  7. #7
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    Either the fuel is too big, or the air is too small.
    There are other 650s running 73/80, so I doubt your fueling side of 69/75 is too fat.
    Remove all four high speed bleeds and note the size, and whether they're clear. Gary
    Regards, Gary

  8. #8

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    Okay tonight I changed the rear main jets to #65. At WOT it goes at 10 and if let my foot on WOT it goes slowly at 11.5-12. I'll check tomorrow the high speed bleeds and I'll let you know! Thanks for the help!

  9. #9

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    The size of high speed bleeds is #41. And they're clean.

  10. #10
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    Default

    Is this a whole new combination, engine rebuild, etc.?
    I'd be trying another carburettor as a quick test.
    Regards, Gary

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