Ferrari 412 Cylinder Compression Test | FerrariChat

Ferrari 412 Cylinder Compression Test

Discussion in '365 GT4 2+2/400/412' started by 360modena2003, Jan 17, 2022.

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  1. 360modena2003

    360modena2003 Formula 3

    Jul 11, 2009
    2,399
    #1 360modena2003, Jan 17, 2022
    Another box ticked off my list.

    The compression is very healthy, what is considered "normal" for the 412?

    I opened the throttle plate to WOT, disconnected both fuel pumps and also disconnected the multiplex ignition controler under the steering wheel (this is done to avoid any possible damage occuring to the ECU when the spark plug is not grounded). Image Unavailable, Please Login

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  2. Il Tifoso

    Il Tifoso Formula 3
    Owner Silver Subscribed

    Oct 22, 2013
    1,551
    SF Bay Area, CA
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    Ruben
    #2 Il Tifoso, Jan 20, 2022
    I’m by no means an expert, but have heard that this is highly variable based on the gauge utilized as well as the state of the battery, so an absolute number is not really meaningful. Rather, what is important, is consistency across all 12 cylinders… the rule of thumb being no more than 10% deviation across all.

    Ruben
     
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  3. Ferrari Tech

    Ferrari Tech Formula 3

    Mar 5, 2010
    1,126
    Georgia
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    Wade Williams
    #3 Ferrari Tech, Jan 26, 2022
    Ruben is correct. There is no actual correct pressure number. Cam timing has a big influence on pressure as well as many other things. So, consistency is key. 10% is a good rule of thumb. You are just looking for something way off. I have had engines that are 210 ish on one bank and 175 ish on the other. It was corrected with proper cam timing.
    If you are 190 ish on all 12, good for you. Proceed with a smile.
     
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  4. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    34,121
    Austin TX
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    Brian Crall
    #4 Rifledriver, Jan 28, 2022
    On a 12 cylinder always have a jumper battery connected. It would be the rare battery that maintained good consistent cranking speed for all 12 cylinders.
     
  5. 360modena2003

    360modena2003 Formula 3

    Jul 11, 2009
    2,399
    #5 360modena2003, Jan 28, 2022
    With all spark plugs removed the battery had no problem cranking all 12.



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