Ferrari 412 - Failed Inspection. High HC and CO Values | Page 6 | FerrariChat
Buy

Ferrari 412 - Failed Inspection. High HC and CO Values

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

This site may earn a commission from merchant affiliate links, including eBay, Amazon, Skimlinks, and others.

Page 6 of 8
  1. 360modena2003

    360modena2003 Formula 3

    Jul 11, 2009
    2,435
    #126 360modena2003, Jun 15, 2023
  2. tazandjan

    tazandjan Three Time F1 World Champ
    Lifetime Rossa Owner

    Jul 19, 2008
    39,046
    Clarksville, Tennessee
    Full Name:
    Terry H Phillips
    #127 tazandjan, Jun 15, 2023
    Kind of hard for 7 to be more accurate than 12 when they are mechanically locked together.
     
    Rifledriver and Steve Magnusson like this.
  3. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,580
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #128 Steve Magnusson, Jun 15, 2023
    +1 -- that would be a bad sign for cam lobe wear if they don't agree well (on different flywheel revolutions).
     
  4. 360modena2003

    360modena2003 Formula 3

    Jul 11, 2009
    2,435
    #129 360modena2003, Jun 15, 2023
    It is only "kind of hard" to understand if you have never done it yourself or don't understand all the factors at play; you are not taking many factors into account like cam lobe wear, valve clearance, tappet wear, valve seat wear, etc.
     
  5. 360modena2003

    360modena2003 Formula 3

    Jul 11, 2009
    2,435
    #130 360modena2003, Jun 15, 2023
    The compression values have all shot up, incredible what a small difference makes; and this with the engine just turning with the starter. I wonder if the differences would be even more pronounced when the engine is running.
     
  6. 360modena2003

    360modena2003 Formula 3

    Jul 11, 2009
    2,435
    #131 360modena2003, Jun 15, 2023
    I've made this simple graph to "pass down" what I am learning. These are the markings on the flywheel as if one was looking at it from the front TO the rear of the car.

    The moment of "revelation" was when Rifledriver noticed that my cam marks were nearly spot on; which invariably means it has not been timed correctly, or better said, not timed AT ALL :)

    Again, the marks on the cam are merely "initial assembly" marks and should not be used for any other purpose other than that; the cams MUST be timed using the marks on the flywheel.

    Image Unavailable, Please Login
     
  7. 360modena2003

    360modena2003 Formula 3

    Jul 11, 2009
    2,435
    #132 360modena2003, Jun 16, 2023
    Just to settle a confusion and correct my statement for anyone in the future attempting to do this:

    Both #12 and #7 can be used for timing the cams, provided that the camshafts are in the overlap phase (not compression).
     
  8. 360modena2003

    360modena2003 Formula 3

    Jul 11, 2009
    2,435
    #133 360modena2003, Jun 16, 2023
    Another adventure for today:

    I have done all the cam timing without the 0.5mm clearance, today I will measure the clearance on the 4 valves and have the machine shop make 4 shims so that I have the required clearance.

    Will be interesting to see how many degrees of timing will yield.

    The added clearance will result in more advance, as it will allow for the lobe to be rotated further before it makes contact with the valve shim.

    The added advance will also result in higher compression.
     
  9. Ferrari Tech

    Ferrari Tech Formula 3

    Mar 5, 2010
    1,205
    Georgia
    Full Name:
    Wade Williams
    #134 Ferrari Tech, Jun 16, 2023
    If you haven't used 0.5mm clearance to set the timing, what have you used. And why would you make a special shim? Just put a thicker shim that has zero clearance and rotate the cam to 0.5mm of valve movement. That is where the opening and closing should happen. It is the most accurate way to know where the cam is, no clearance means the number you see are always from actual cam movement. If you have 0.5 clearance you then have to wait for contact and movement to register a position. That is just adding another variable.
     
  10. 360modena2003

    360modena2003 Formula 3

    Jul 11, 2009
    2,435
    #135 360modena2003, Jun 16, 2023
    I am using my shims that give 0.20mm and 0.30mm valve clearance.

    The specified valve clearance during the cam timing is 0.5mm.

    The start of the intake valve "Event", AA16, is determined (ideally with a dial indicator) when the lobe on the camshaft starts to push down on the shim/tappet/valve stem. How far the camshaft needs to turn until it makes contact will (also) depend on how much clearance there is; put in simple terms: more clearance /valve lash, the more the camshaft will need to turn (advance) to initiate the intake valve opening.

    Sent from my MAR-LX1M using Tapatalk
     
  11. 360modena2003

    360modena2003 Formula 3

    Jul 11, 2009
    2,435
    #136 360modena2003, Jun 16, 2023
    Perhaps this assists in understanding - GREEN being exaggerated valve clearance, RED no clearance and YELLOW rotation of the camshaft.

    Image Unavailable, Please Login
     
  12. 360modena2003

    360modena2003 Formula 3

    Jul 11, 2009
    2,435
    #137 360modena2003, Jun 16, 2023
  13. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    36,816
    Cowboy Capitol of the World
    Full Name:
    Brian Crall
    #138 Rifledriver, Jun 16, 2023
    You have obviously never used the Ferrari method. I have, many times. Its very repeatable, accurate and works great. It also eliminates the need for any special tools or knowledge of using them.
     
  14. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    36,816
    Cowboy Capitol of the World
    Full Name:
    Brian Crall
    #139 Rifledriver, Jun 16, 2023
    Tappet wear or valve set wear cannot possibly cause you an issue. If the cam was worn as suggested it would be obvious and you would have much bigger trouble.
     
    tbakowsky likes this.
  15. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    36,816
    Cowboy Capitol of the World
    Full Name:
    Brian Crall
    #140 Rifledriver, Jun 16, 2023

    Making and using teflon shims is a really bad idea. As I have stated off line, this needs to be done according to my instructions. Using teflon shims was not one of them.

    The first time a cam lobe passes over it will be the last time it measured .5mm

    This is why I no longer have employees. I will not stand over someone to be sure they have not decided yet again to do it their way.
     
  16. 360modena2003

    360modena2003 Formula 3

    Jul 11, 2009
    2,435
    #141 360modena2003, Jun 16, 2023
    The machinist bet me a beer it would read consistent 0.50mm for at least 10 full revolutions.

    Teflon is used in many industrial applications as bearing carriers, as well as in suspension bushings to very exact tolerances.

    Sent from my MAR-LX1M using Tapatalk
     
  17. raemin

    raemin Formula 3

    Jan 16, 2007
    2,288
    Lyon (FR)
    Full Name:
    R. Emin
    #142 raemin, Jun 16, 2023
    Teflon is soft, not sure how it will retain its flat shape in the cam follower.

    If your machinist looses his bet, discard the beer and take his comparator. You could then give @Ferrari Tech method a try... Measure your current gap (with your regular shims), and check with the comparator for the additional valve lift to reach 0.5mm.
     
  18. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    36,816
    Cowboy Capitol of the World
    Full Name:
    Brian Crall
    #143 Rifledriver, Jun 16, 2023

    Good luck with the car.
     
    Island Guy likes this.
  19. Ferrari Tech

    Ferrari Tech Formula 3

    Mar 5, 2010
    1,205
    Georgia
    Full Name:
    Wade Williams
    #144 Ferrari Tech, Jun 16, 2023
    Rifledriver is correct. I haven't used the Ferrari WSM method, I have always used a degree wheel. If I am using the Ferrari / flywheel mark, how do I know the valve is at .05 if you don't use a dial indicator? I don't have my 412 WSM handy to look at it. I am just learning new stuff here, I really like understanding different methods.
    I agree that the teflon is a bad idea, but I am waiting with my popcorn to hear how it goes.
     
    raemin likes this.
  20. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    13,413
    San Carlos, CA
    Full Name:
    Mitchell Le
    #145 yelcab, Jun 16, 2023
    1. You line up the flywheel at the mark (AA16 for example) where you are checking.
    2. You uncouple the cam shaft sprocket from the cam shaft so they no longer turn with each other,
    3. You turn the camshaft such that the vavle bucket transitions from "able to rotate" to "unable to rotate" (or vice versa depending on whether the event is opening a valve or closing a valve)
    4. You reconnect the cam shaft to the pulley

    If more explanation is needed, then this WSM method is not for you.
     
  21. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    36,816
    Cowboy Capitol of the World
    Full Name:
    Brian Crall
    #146 Rifledriver, Jun 16, 2023
    Are you serious? You take money from people to fix their Ferrari ?
     
  22. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    36,816
    Cowboy Capitol of the World
    Full Name:
    Brian Crall
    #147 Rifledriver, Jun 16, 2023
    Fastest, easiest way on the old front engine cars. We used to do it every major to correct for chain stretch.

    But I am done here so help your self. I don't cope well with people who blow off instructions. Its bad enough someone who never heard of overlap had decided his calling is 4 cam Ferrari motors.
     
  23. tbakowsky

    tbakowsky F1 World Champ
    Consultant Professional Ferrari Technician

    Sep 18, 2002
    19,855
    The Cold North
    Full Name:
    Tom
    #148 tbakowsky, Jun 16, 2023
    Actually..I tested this method on a 456..it does kinda work. It is not ideal..but for poops and giggles..I wasn't that far off..
     
    360modena2003 likes this.
  24. 360modena2003

    360modena2003 Formula 3

    Jul 11, 2009
    2,435
    #149 360modena2003, Jun 17, 2023
    Last edited: Jun 17, 2023
    Will be interesting to see. Teflon is not soft, according to DIN 53456 (load 13,5 Kg for 30 sec) the hardness is between 27 and 32 N/mm2 (3.2KG/mm2).

    The shims are 33mm in diameter, which gives us a total surface area of 855.3mm2 = so 2500+ KG. Yes, I am aware that the edge of the lobe will not make contact with the entire surface, but the spring force of the valves is that the most 4% of that (100KG).

    Also consider that the timing is done with the cam lobe "resting" on the shim, where there is no load.

    Get the popcorn, beer, and Prosecco out.
     
  25. 360modena2003

    360modena2003 Formula 3

    Jul 11, 2009
    2,435
    #150 360modena2003, Jun 17, 2023
    Done, and I lost the bet. Had consistent 0.5mm clearance with the shims, even after 4-5 rotations.

    Compression has gone by 5 to 10 psi, reading between 165 and 155 now.

    Now the initial assembly marks are even closer. Image Unavailable, Please Login

    Sent from my MAR-LX1M using Tapatalk
     
Page 6 of 8

Share This Page