cam timing questions | FerrariChat

cam timing questions

Discussion in 'Boxers/TR/M' started by tommie, May 20, 2014.

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  1. tommie

    tommie Rookie

    Feb 28, 2013
    42
    when degreeing the cams on cyl 7-12 am i to use cyl 7 for tdc?
     
  2. turbo-joe

    turbo-joe F1 Veteran

    Apr 6, 2008
    9,531
    southwest Germany, France ( Alsace ) and Thailand
    Full Name:
    romano schwabel
    when you use a grade scale then: yes - but then also you have to adjust the valve clearance to 0,5 mm for the 1st and 7th cylinder
    if you use the marks on the cams then all those 4 marks on the cams are only good if the cyl 1 is in TDC
     
  3. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    13,566
    San Carlos, CA
    Full Name:
    Mitchell Le
    You can use any cylinder as long as you start with that cylinder at TDC.
     
  4. tommie

    tommie Rookie

    Feb 28, 2013
    42
    thanks i must be doing something wrong
    did cyl 1-6 all worked out ok
    with doing cyl 7-12 and the fly wheel on the correct mark for 7-12 cyl 7 at true tdc
    my intake cam timing seams way off i wind up with it opening 10 degrees after top dead center and not before
    others have commented not to use marks on cams since it was only for assembly reasons and not 100 % accurate for cam timing?
     
  5. tommie

    tommie Rookie

    Feb 28, 2013
    42
    so joe am i to adj the valve clearance to .5mm meaning ? shim pack adj?
    i thought i was to read degree well indication when dial indicator which is on the shim pack reads .5mm movement from seated position ?
     
  6. turbo-joe

    turbo-joe F1 Veteran

    Apr 6, 2008
    9,531
    southwest Germany, France ( Alsace ) and Thailand
    Full Name:
    romano schwabel
    the timing marks at the cams are so, that you put cyl. 1 to TDC and the 4 marks at the cams may match with the marks on the upper half shells of the camshaft bearings. if you adjust so the engine will always run, but it is not perfect. the marks on the cams cyl. 7 to 12 has nothing to do with the TDC of one of those cylinders, because cyl 1 has to be in TDC as I remember right??? but I will have a look later in my basement where there are 2 more TR engines to make sure. but also in the WSM it says the same.

    the "test valve clearance" to adjust right the timing is 0,5 mm. so you may use a shim that the clearance then between the cam and this shim is 0,5 mm, but don´t forget after this adjustment to change again the shim to the right size
     
  7. turbo-joe

    turbo-joe F1 Veteran

    Apr 6, 2008
    9,531
    southwest Germany, France ( Alsace ) and Thailand
    Full Name:
    romano schwabel
    I just come out of my basement and have to cofirm what I have written before:

    the marks on the cams are ALL for cyl. 1 is in TDC

    so when you turn the crankshaft 720 ° that cyl. 1 is again in TDC then all marks on the cams have to be equal with the marks at the housing
     
  8. wintech

    wintech Karting

    Jun 1, 2011
    206
    Perth WA
    Full Name:
    Pete K
    Hi Tommie,
    There are a lot of threads on this forum regarding opening lift and cam duration. I set the cams on mine a few months back while doing the major service.

    First off, the diagram in the WSM shows the rotation counterclockwise, that is an error as one member has posted an amended pdf diagram which makes more sense.

    Second, the confusion of what is termed át .5 lift' for the duration checking was confusing; as too many opinions have been posted. I had to apply commonsense and trial and error to get it right.

    The degree wheel has to be reset to 0deg TDC for #1 and #7 . IIRC the lift referred to is the distance the valve has moved off its seat for the opening duration to begin and it returns to that setting(.5mm) for the conclusion of the closing travel. If your shim clearance is correct on all of yr valves (inlet and exhaust clearance) then the duration at .5mm lift and back to .5mm again as it closes will correspond to the degrees of duration for each of the inlet and exhaust durations stated in the WSM.

    One thing I found was, 2 of my valves had extra clearance of .02mm, a seemingly insignificant amount; however the amount of cam rotation used to get the valve to .5mm lift is reducing the duration of the valve being open for its optimum efficiency. In other words, it opens quite few degrees late and closes an equal number early.

    If you are not aware of the amount of variation between the shim clearances, you may well chase yr tail for quite a while thinking the cams are out...but in reality it is showing the opening at .5mm lift later and showing the close earlier. I took the rotational duration for each in/exh duration and it was the same angular variation each side of the 'segment' which confirmed the open/close- before/after TDC/BDC.

    I hope this has been of some help if it is decipherable - as comprehension and explanation are sometimes not a given.

    Cheers
    Pete
     
  9. tommie

    tommie Rookie

    Feb 28, 2013
    42
    pete thanks soo much for your feed back
    i'm just getting back to this and am still confused a little?

    cyl. 1 seamed to work out ok
    now doing other back 7-12
    checking cyl.7 with .009/.229mm tappet clearance`
    intake opens 12 degress atdc and not 13 btdc and
    closes 74 degress abdc
    thats using .5mm movement on the tappet shim pack?

    so it looks like due to shim clearance ? intake opens late
    closes early?
    boy i seam to be going in circles on this
    worried about putting eng back in and it not running correct
    using factory cam ca`p marks
    with #1 tdc intake cam cap lines up on bank 1-6 but exh of 1` notch
    on bank 7-12 both intake and exh marks of same amount
    thanks
    tom
     

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