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Valve Shim Measurement on 84 308

Discussion in 'Technical Q&A' started by Wildcatfans, Jul 20, 2004.

  1. Wildcatfans

    Wildcatfans Karting

    Sep 4, 2001
    247
    Baton Rouge
    Full Name:
    Donny Bridges
    I'm in the middle of a 30 k service and now ready to adjust the valve clearances. I have measured the gap and now have some questions.

    What is the target value for the intake and exhaust valves? I understand the spec ranges from .20-.25mm for intake and .30-.35mm for exhaust, however is it better to be on the low or high side of the range?
    These are the clearances I measured:
    Intake, .24, .28, .26, .23, .24, .24, .24, .22, .24, .21, .24, .23, .21, .23, .24, .28
    Exhaust, .39, .38, .35, .43, .39, .39, .36, .34, .36, .38, .35, .41, .31, .39, .36, .33

    Next question, when using the spring compression tool, #AS9560, is there a concern in how far down to compress? My concern is driving the valve into the piston while trying to create enough space to remove the shim. I compressed the shim/bucket about half way down but this wasn't enough to remove the shim from underneath the cam. The Ferrari workshop manual says nothing about how far down to go.

    Thanks for any information.

    Donny
     
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  3. Ferrari_tech

    Ferrari_tech Formula 3

    Jul 28, 2003
    1,527
    UK
    Full Name:
    Malcolm W
    Donny,

    Since the engine has done 30k, one would assume that valves etc. have all settled in and that there won't be any major changes to valve clearances from now on.

    Where you set them in the parameters given by Ferrari is up to you and can depend on the type of use you are going to give the car (ie. lots of track use). For regular useage and "spirited driving" I would aim at somewhere in the middle of the recommended settings, but having said that, for example with your measurment of .24 / .21 although they are towards the end of the scale I wouldn't re-set the clearance.

    A small point to consider, even if the clearance is okay, still remove the shim and inspect it for cracks / uneven wear.

    If using the correct tool to compress the bucket you will not damage the valve / piston, if you have to depress the bucket a little bit further to remove the shim the likely-hood of damage is remote.

    I always, as stated in the manual used compressed air to remove the shim, can be a bit messy with oil being blown everywhere, but you can use a small probe in the slot in the bucket to prise out the shim - be careful though not to "bruise" the edge of the bucket.
     

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