Ferrari V12 Engine Diagnostics. High Compression/Low Vacuum | FerrariChat
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Ferrari V12 Engine Diagnostics. High Compression/Low Vacuum

Discussion in 'Technical Q&A' started by 360modena2003, Apr 18, 2024.

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  1. 360modena2003

    360modena2003 Formula 3

    Jul 11, 2009
    2,460
    #1 360modena2003, Apr 18, 2024
    Hello,

    I am trying to diagnose the cause of low vacuum/low power on my Ferrari 412 engine.

    i just did a compression test and have 155 to 165 across all 12 cylinders.

    The assumption is that I may have a valve/camshaft timing issue, but is it possible to have incorrect timing and high compression?

    The engine starts but has barely any power (I have removed the exhaust and the air filters to rule out any restrictions).

    I have also tested fuel pressure (3 BAR control pressure, 5 BAR system pressure) and volume 850ccm3, and all within spec - same with ignition timing.
     
  2. raemin

    raemin Formula 3

    Jan 16, 2007
    2,388
    Lyon (FR)
    Full Name:
    R. Emin
    #2 raemin, Apr 18, 2024
    Maybe you should revert to the factory timing marks and see if it gets any better?

    If you just take note of where the pins are on the sprookets, you can easily revert back to your current settings if need be.

    Have you checked that all the valves that adjust vacuum are properly working? The k-jet has an air bypass that allows to drop vacuum when you unload the engine. This one could be faulty. The same goes for the vacuum amplifier used for the gearbox, as well as the brake booster. I would check all these for a leak.

    Finally the ignition timing also has a vacuum port (that's specific to the 412). So if your vacuum is wrong, this is probably playing havoc with the ignition.

    Last but not least, it seems strange that both sides are weak. Wrong valve timing on both sides would be odd.
     
  3. 360modena2003

    360modena2003 Formula 3

    Jul 11, 2009
    2,460
    #3 360modena2003, Apr 18, 2024
    UPDATE: I've discovered the issue!!!
     
  4. flash32

    flash32 F1 Veteran

    Aug 22, 2008
    7,083
    Central NJ
    Full Name:
    Dominick
    #4 flash32, Apr 18, 2024
    And ?
     
  5. Chindit

    Chindit Formula Junior
    Owner Silver Subscribed

    Oct 18, 2008
    427
    Navarre, Florida
    Full Name:
    Nick P.
    #5 Chindit, Apr 19, 2024
    Vacuum leak?
     
  6. raemin

    raemin Formula 3

    Jan 16, 2007
    2,388
    Lyon (FR)
    Full Name:
    R. Emin
    #6 raemin, Apr 19, 2024
    This was adressed in the other thread... one bank did not have spark. Unlike the older 400, the 412 does have a twin ingnition module & twin coil setup, so you can end up with an inline 6.
     
    Chindit likes this.

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