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Thread: 477 BBC HIGH RPM MISFIRE

  1. #1
    Junior Member APPRENTICE
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    477 BBC HIGH RPM MISFIRE

    I have been fighting this for long enough... 477 BBC Dart pro 1 heads, Roller, 13:1, BG 400 pump (new), Quick Fuel 1050 Alch, MSD Distributor ignition.
    Between the 1 -2 shift the car started popping slightly, steadily got worse. EGT was reading high. Put larger jet in carb. Kept getting worse as time went bye. Don't race alot so a few weeks go bye between attemts to cure. Thought it was a fuel delivery problem. Ordered new BG 400 pump and 4 port reg. Installed but no cure. Got up to almost 200 jets and still had hot EGT temps. Winter came a I said I'll see you next year.
    Ordered new valve springs and installed. Went out today and problem still there. Any other things I am missing? I am probably looking over the problem so don't be afraid to mention some silly questions at this point.

    Thanks in advance.

  2. #2
    Senior Member RACING JUNKIE
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    What kinda fuel pressure ?

    Also when you were putting bigger jets in the carb was the egt going higher or lower ?

    What fuel ya use ?
    David Lanning
    IHRA NHRA 387B

    Fleenor Racing Transmission
    419-280-1406
    Lanning Electric
    Complete Drag Car Wiring
    APD Race Engines
    www.apdracing.com

  3. #3
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    I have 8 to 9 lbs of fuel pressure. When I started changing jets, The EGT did not change or got worse. I am i at 1335 degrees and only running 1/8 mile.

  4. #4
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    Sorry. I use V/P alch.

  5. #5
    Senior Member RACING JUNKIE
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    Quote Originally Posted by bajaboat32
    I have 8 to 9 lbs of fuel pressure. When I started changing jets, The EGT did not change or got worse. I am i at 1335 degrees and only running 1/8 mile.
    changing jets didnt move the egt at all ? I assume you checked the float level already ?

    Which VP fuel the normal m1 or m5 ?
    David Lanning
    IHRA NHRA 387B

    Fleenor Racing Transmission
    419-280-1406
    Lanning Electric
    Complete Drag Car Wiring
    APD Race Engines
    www.apdracing.com

  6. #6
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    Yes float levels been checked. I guess M1 on the fuel.

  7. #7
    Senior Member RACING JUNKIE
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    increase the fuel pressure some and see what happens, could be a bad gauge and be lower then actual ?
    David Lanning
    IHRA NHRA 387B

    Fleenor Racing Transmission
    419-280-1406
    Lanning Electric
    Complete Drag Car Wiring
    APD Race Engines
    www.apdracing.com

  8. #8
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    Did that. Put a second gauge on it and it is set now just before it runs past seat.

  9. #9
    Senior Member RACING JUNKIE
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    what high side chip does it have in it ?
    David Lanning
    IHRA NHRA 387B

    Fleenor Racing Transmission
    419-280-1406
    Lanning Electric
    Complete Drag Car Wiring
    APD Race Engines
    www.apdracing.com

  10. #10
    Junior Member APPRENTICE
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    Set to 7600. But now I can't even get to the shift point to make it shift it pops so bad. Shift point is at 6500.


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