Ferrari 400/412 Camshaft Timing. Required Valve Clearance and Effect Timing and Dynamic Compression. | FerrariChat
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Ferrari 400/412 Camshaft Timing. Required Valve Clearance and Effect Timing and Dynamic Compression.

Discussion in 'Technical Q&A' started by 360modena2003, Jun 16, 2023.

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Ferrari 412 Cam Timing: How many degrees timing will result from using 0.5mm vs 0.2/0.3mm clearance?

  1. MORE THAN 3 degrees.

    2 vote(s)
    100.0%

  2. LESS THAN 3 degrees.

    0 vote(s)
    0.0%

  3. MORE THAN 5 PSI compression

    1 vote(s)
    50.0%

  4. LESS THAN 5 PSI compression.

    0 vote(s)
    0.0%
Multiple votes are allowed.
  1. 360modena2003

    360modena2003 Formula 3

    Jul 11, 2009
    2,460
    #1 360modena2003, Jun 16, 2023
    After delving deeper into the particularities of setting valve timing, and only after member(s) of this forum kindly pointed out that my valve timing was obviously off (as I only used the initial assembly cam marks for timing the valves), I am now understanding the principles behind the process.

    I have now set up my timing, but have not yet used the specified valve clearance of 0.5mm when setting the timing.

    Today I will have the machine shop fabricate shims so that the valve clearance is 0.5mm on the 4 valves of cylinder #1 and #7 and then re-set the timing.

    Will be interesting to see how much this results in additional advance and added dynamic compression.

    Take your bets - I believe I should be getting at least 5 PSI more in compression.
     
  2. Ferrari Tech

    Ferrari Tech Formula 3

    Mar 5, 2010
    1,233
    Georgia
    Full Name:
    Wade Williams
    #2 Ferrari Tech, Jun 16, 2023
    Last edited: Jun 16, 2023
    Just put a thick shim in that results in zero clearance and then have the timing set when the valve moves 0.5 mm. You don't need a special shim.
     
    flash32 likes this.
  3. wmuno

    wmuno Formula Junior
    Silver Subscribed

    Dec 24, 2007
    522
    Wilmette, Illinois
    Full Name:
    Bill Muno
    #3 wmuno, Jun 17, 2023
    I wouldn’t get overly concerned about the compression numbers. There are many factors that affect the compression numbers that have nothing to do with valve timing. Follow the instructions you have been given to set the valve timing correctly. I’m certain your engine will run much better.
     
  4. 360modena2003

    360modena2003 Formula 3

    Jul 11, 2009
    2,460
    #4 360modena2003, Jun 17, 2023
  5. tbakowsky

    tbakowsky Two Time F1 World Champ
    Consultant Professional Ferrari Technician

    Sep 18, 2002
    20,044
    The Cold North
    Full Name:
    Tom
    #5 tbakowsky, Jun 17, 2023
    Assembly marks are usually about 10-15 degrees out. I have checked this in the past. However, I have had some instances where one or 2 cams are spot on..but never all 4.
     
  6. 360modena2003

    360modena2003 Formula 3

    Jul 11, 2009
    2,460
    #6 360modena2003, Jun 17, 2023
    Very interesting point, in my case some were right on, others less so.

    Will post pictures of the assembly marks later.

    Sent from my MAR-LX1M using Tapatalk
     
    tbakowsky likes this.

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