Valve timing | FerrariChat

Valve timing

Discussion in '365 GT4 2+2/400/412' started by moserpe, Jan 17, 2008.

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  1. moserpe

    moserpe Karting

    Jul 20, 2006
    137
    Switzerland
    Full Name:
    Peter Moser
    #1 moserpe, Jan 17, 2008
    Last edited by a moderator: Sep 7, 2017
    Not knowing if and when the valve clearance had been adjusted before i owned the car, i decided to do this check. After removal of the valve covers i found something strange: The relative cam positions (inlet and exhaust) was completely different at the right and left cylinder banks (upper picture shows right bank, lower pic for left bank). All four camshafts have correctly aligned marks for TDC 1/6! Guess what is wrong!
    Exhaust and inlet camshafts of the left bank are swapped! It is sheer luck that the valves did not hit the pistons. The only problem were the emissions of the left bank and no doubt, the fuel consumption was too high and the performance too low, but you do not notice with the 12 cylinders! May be that also the slight vibrations at idle will disappear. I'm definitely looking forward to a different driving experience.

    Even a low mileage car is not necessarily free from unprofessional work, even if it was always "maintained by a real Ferrari expert" as the previous owner said.
    The valve clearance is generally too small and needs adjustment as well.

    Peter
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  2. Hans

    Hans F1 Veteran

    Feb 17, 2006
    7,734
    Hilversum, Netherlands
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    Hans Teijgeler
    Holy sh**. Good find!!!!!

    I bet you'll enjoy your silky smooth ride once they're done :)

    Are there any GOOD 400's out there, or are they all cursed with something that's wrong, and it's just up to the new owner to figure out what that something is?

    Hans

    Edit: I just went through your web site. You've certainly done a LOT of work on your 400. Hats off to you!!
     
  3. Artvonne

    Artvonne F1 Veteran

    Oct 29, 2004
    5,379
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    Paul
    I dont know if what your seeing is not actually correct. No cam lobe can ever be in the same position of any others in ANY engine, Ferrari notwithstanding. Even on the 308, when one bank has a cylinders lobes facing one way, the other bank will have lobes on the opposing bank facing the other direction. Before you start ripping it all apart to correct something that may not be required, I would check it carefully with a degree wheel and a dial indicator and verify the physical valve timing. Actually, you could just watch the distributor rotor march around while watching cam lobes and get a good idea if its right. I would also check carefully for any part numbers on the camshafts, and try to verify that they are correct, as well as in thier correct locations. If the actual valve timing was off more than a few degrees either direction on one bank, it would lose a great deal of power. And if it were off fully 180 degrees on one bank, it would only pop and backfire on that bank and probably wouldnt even rev enough to be able to drive it. I guess what I am saying is that if the engine ran decent and had good power, you should assume its very very close to being where it needs to be, and what your seeing is playing tricks on your eyes. Dont feel bad, weve all been fooled by engines before. And the more complicated they get, the easier it becomes. I still screw myself up on the 308 trying to time the cams, because the cams rotate in reverse to normal engine rotation. Trying to watch the cams turn backwards while turning the engine forwards and remaining focused on BTDC and ATDC valve timing, sometimes I have to turn away or close my eyes for a minute to re-focus my thinking. Sometimes I have to physically walk away for a moment and not look at it while I sort my thoughts. Im pretty sure im not alone on that deal.
     
  4. moserpe

    moserpe Karting

    Jul 20, 2006
    137
    Switzerland
    Full Name:
    Peter Moser
    Hi Paul,

    May be your comment has enlightend me! I did not consider that intake and exhaust side are the opposite (always seen from the front) which explains the different relative position of exhaust and intake cams! Looks very much I have to learn more about V-type engines! Seeing the different appearance I jumped to the (wrong) conclusion because it might have explained the initial emissions problems of the left bank as well.
    In the meantime I have made a manual mechanism in place of the starter motor to smoothly revolve the engine which will allow me to verify the valve timing as you have suggested. The visual impression of too much valve overlap may hopefully be proven wrong.
    It will also give me the confidence back that the engine with 45000 kms only has not been taken apart so far.

    Sometimes you have to start stupid to become wise!

    Thanks for your input

    Peter
     
  5. markcF355

    markcF355 F1 Rookie
    Rossa Subscribed

    Jun 6, 2004
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    Mark
    As I remember it, the cams don't have part numbers on them. You can tell them apart by the amount of lift.
     
  6. ricar116

    ricar116 Formula Junior

    Aug 2, 2005
    409
    Bolivar, Missouri
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    Rick Carr
    The readjusted "tight valves" may make more of an improvement than you might expect.
    Rick
     
  7. fastradio

    fastradio F1 Rookie
    BANNED Professional Ferrari Technician

    Apr 26, 2006
    3,664
    New England
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    David Feinberg
    Peter,

    Paul comments are spot on...The eyes and mind can play tricks on you when assessing cam positions, even after many years of working on these cars. I remember vividly questioning the cam lobe positions when I first did belts on a Boxer. And, to add insult to injury, the diagram in the WSM was "incorrect" to boot...Anyhow, looking at your pictures, the lobes, on all banks...are in the correct relative postions. No doubt, here...

    I believe you'll find the marks "I" and "S" stamped into the cams, towards the timing gears; "I" being intake and "S" being exhaust.

    Regards,
    David
     

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