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Ferrari 412 - Failed Inspection. High HC and CO Values

Discussion in 'Technical Q&A' started by 360modena2003, Jun 6, 2023.

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  1. Rifledriver

    Rifledriver Three Time F1 World Champ

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    #101 Rifledriver, Jun 14, 2023
    A physical impossibility and makes me question your methodology.

    Those marks are so far off you have done something very wrong.

    With 7 at overlap valves are in exactly the same position relative to the pistons with timing marks aligned as on cylinder # 12.
    Or the other possibility is I have been doing it all wrong for the last 45 years and do not understand 4 stroke engines.

    This is why I am reluctant and never will again help those with so little knowledge get out of a mess of their making. Leave this kind of work to capable people.
     
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  2. Ferrarium

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    #102 Ferrarium, Jun 14, 2023
    "touching against the piston"

    It takes very little for the piston to bend that valve head btw, don't even know it happens most times unless your very experienced. Be sure to check that cylinder seals at top of the compression stroke.


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  3. 360modena2003

    360modena2003 Formula 3

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    #103 360modena2003, Jun 14, 2023
    Will go over it again tomorrow, the exhaust seems to be right, as there is evidence of a mark that lines up.

    It can be that the shim we used did not give the correct 0.5mm clearance.

    The 1-6 bank gave me 150 psi, whereas the 7-12 consistent 125 psi, so it could be that the exhaust is off by a few degrees.



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  4. 360modena2003

    360modena2003 Formula 3

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    #104 360modena2003, Jun 14, 2023
    As I already mentioned, there is no one capable or interested in doing this kind of work where I am.

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  5. raemin

    raemin Formula 3

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    #105 raemin, Jun 14, 2023
    Given the loss of dynamic compression, I would assume the inlet was retarded too much.
     
  6. Rifledriver

    Rifledriver Three Time F1 World Champ

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    #106 Rifledriver, Jun 14, 2023
    Then maybe consider a Mercedes.
     
  7. 360modena2003

    360modena2003 Formula 3

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    #107 360modena2003, Jun 14, 2023
    Will advance a mm and re-test.

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  8. 360modena2003

    360modena2003 Formula 3

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    #108 360modena2003, Jun 14, 2023
    Right bank is right on...will go over left bank again tomorrow.

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  9. 360modena2003

    360modena2003 Formula 3

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    #109 360modena2003, Jun 14, 2023

    Am I right in understanding that when #7 is at overlap, #12 should be in the compression stroke?
     
  10. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #110 Steve Magnusson, Jun 14, 2023
    Yes -- the AA16 and CS10 marks for cyls #7 and #12 are in the same place on the flywheel but they are "separated" by one full revolution.
     
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  11. Ferrari Tech

    Ferrari Tech Formula 3

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    #111 Ferrari Tech, Jun 14, 2023
    I am with Rifledriver on this one. If 7 hit and 12 didn't something was done wrong.
     
  12. 360modena2003

    360modena2003 Formula 3

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    #112 360modena2003, Jun 14, 2023
    They are not "hitting", only if I try to align #7 to the AA16 and CS10 marks on the flywheel.

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  13. raemin

    raemin Formula 3

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    #113 raemin, Jun 14, 2023
    As a rough guess I would say he did it wrong on cyl #7 due to the painfull access. More room to do it properly on #12.

    To give you an idea that's my mechanic working there...

    Image Unavailable, Please Login
     
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  14. 360modena2003

    360modena2003 Formula 3

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    #114 360modena2003, Jun 15, 2023
    There is plenty of access.

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  15. 360modena2003

    360modena2003 Formula 3

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    #115 360modena2003, Jun 15, 2023
    Yes, and therefore you can only one #7 OR #12 alignment if you want your alignment near the cam marks . In my case my marks are near alignment with #12.

    In order to do alignment with #7 I would need to do one full rotation so #7 is at overlap.

    I think I have come up with a great idea: I will slowly advance my intake cam until my compression matches bank 1-6. I will start by advancing 2 degrees and see what I get.
     
  16. raemin

    raemin Formula 3

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    #116 raemin, Jun 15, 2023
    Are you sure the compression is homogeneous accros all cylinders? Based on the different outcome when working on #7 and #12, I would assume that you either did it wrong (you said you didn't), or the camshafts lobes are not symmetric any-more (but compression should be different).

    You've added a significant amount offset, backing out in order to get closer to the base setting seems quite reasonable. So your "great idea" will not be everyone's cup of tea, but at least it's a "less risky bet".
     
  17. 360modena2003

    360modena2003 Formula 3

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    #117 360modena2003, Jun 15, 2023
    Last edited: Jun 15, 2023
    Yes, bank 1-6 have all consistent 150 PSI, while all 6 cylinders on 7-12 have nearly exact 125 PSI - so as you mentioned, the "dynamic compression" is lower due to have less "time" to pull in air. This also matches with Rifledriver's comment that it should not be so far from the initial assembly cam marks - I will move it a few degrees, or better said, a few mm, and then see how it effects the compression. It is very easy to do now that everything is apart.
     
  18. 360modena2003

    360modena2003 Formula 3

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    #118 360modena2003, Jun 15, 2023
    Even the slightest damage on the valve (bending) would show up immediately in the compression test, resulting in near zero compression. I am having the engine turned over by hand, so any interference can be felt easily.
     
  19. Ferrarium

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    #119 Ferrarium, Jun 15, 2023
  20. 360modena2003

    360modena2003 Formula 3

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    #120 360modena2003, Jun 15, 2023
    Last edited: Jun 15, 2023
    Appreciate your suggestion. Will head over to the car now and start experimenting, can't wait. This car provides a lot of entertainment. :)

    I will start with 1mm and then measure compression, will also look the timing with the flywheel with AA16 before and see where the intake cam lobe is resting against the shim.
     
  21. wmuno

    wmuno Formula Junior
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    #121 wmuno, Jun 15, 2023
    Just a suggestion; when you are tuning over the engine by hand, it's much easier with the spark plugs removed. There is very litle danger of something falling into an open spark plug hole.
     
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  22. Rifledriver

    Rifledriver Three Time F1 World Champ

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    #122 Rifledriver, Jun 15, 2023
    Lets stop with the compression tests already. No useful information there. Its a distraction and a waste of time.
     
  23. Rifledriver

    Rifledriver Three Time F1 World Champ

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    #123 Rifledriver, Jun 15, 2023
    Waste of time. Do it once, do it right. Experimentation in a realm you dont understand isn't going to yield any useful data. Lets just do it their way.
     
  24. 360modena2003

    360modena2003 Formula 3

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    #124 360modena2003, Jun 15, 2023
    Just advanced the timing, seems AA16 was not exactly aligned. Redid it and now the compression jumped to 145 PSI.

    Will advance it a bit more.



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  25. 360modena2003

    360modena2003 Formula 3

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    #125 360modena2003, Jun 15, 2023
    Just set it using cylinder #7 and advanced it a bit more, seems #7 is more accurate.

    The compression is now reading 160 PSI!


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