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Original timing marks Camshaft 250 Gte

Discussion in 'Vintage (thru 365 GTC4)' started by christc, Jul 4, 2020.

  1. christc

    christc Formula Junior

    Mar 3, 2013
    312
    Germany
    Hi All,

    my camshafts are marked in two different ways. See picture. One mark is a punch (right in picture) the other a fine line (left in picture). On one camshaft both marks are at the same place, at the other they differ. I guess the thin line is the original factory mark, the punch from a latter timing correction of a workshop. Right? Is the line on the camshaft direct beside the arrow on the valve roller cap the factory mark?

    Thanks
    Christopher

    PS.: clear that I will only use them for basic setting and check/ adjust correct timing afterwards.
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  3. MiuraP400

    MiuraP400 Formula Junior

    Feb 3, 2008
    806
    Arizona
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    Jim
    The circle on the left is factory from what I have seen. I would look at the spocket to see if it has a punch mark. It could be an assembly aid someone added.

    Cheers Jim
     
  4. turbo-joe

    turbo-joe F1 Veteran

    Apr 6, 2008
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    romano schwabel
    exactly
    and don´t forget the valve clearance for adjusting th etiming is 0,5 mm ( when I remember right? )
     
  5. christc

    christc Formula Junior

    Mar 3, 2013
    312
    Germany
    Thanks.

    @turbo-joe
    Are you sure about 0.5?
    The 250 timing instructions and the 330 handbook says to set valve clearance 0.15inlet and 0.2outlet. It says that valve clearance has to be right before setting timing but does not mention a different clearance?

    Thanks
    Christopher
     
  6. turbo-joe

    turbo-joe F1 Veteran

    Apr 6, 2008
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    #5 turbo-joe, Jul 5, 2020
    Last edited: Jul 5, 2020
    best would be to check the complete time the valves ( in - and outlet ) are open, then you see when you count all the degrees together if the timing is in specification or not. but I wonder that the timing will get adjusted with 2 different valve clearances?. never have seen this before on an engine. and all the later timing belt engines from F have those 0,5 mm.

    good is that you only have 1 camshat each cylinder row to adjust. so when you then adjust the timing for the inlet valve and then check the timing for the outlet valve and they are not matching then you know you have wrong timing

    have my infos not here ( still stranded in thailand ) so I not know the opening from the valves in ° crankshaft. but for example when the intake valve will open 25 ° before TDC and will close 30 ° after BTC then the opening time is 25 + 180 + 30 = 235° crankshaft. when you have those 235° with a play from 0,15 mm then it is ok. but when you have only 200 ° then you know the valve clearance with 0,15 is to small for adjusting the timing
     
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  8. christc

    christc Formula Junior

    Mar 3, 2013
    312
    Germany
    Hi,

    I will definitely check exact timing of inlet and exhaust with degree wheel. I will only use factory marks for initial setup. I checked again valve clearance from different sources, all state .15 inlet and .2 exhaust, no different settings for timing.

    @DWR46
    Hello Dyke, I believe some of the instructions I have are from you via the 250Gte forum. Can you confirm valve lash as above also for timing? Thanks a lot.
    Christopher
     
  9. DWR46

    DWR46 Formula 3
    Honorary

    Jun 19, 2012
    1,358
    Christopher: You are correct, 0.15mm for intake and 0.20mm for exhaust cam timing checking for your engine. With the clearances set to these values, the marks on the flywheel should be "close" at the point of intake opening and exhaust closing. However, this method of checking has so many variables (worn cams, rollers, variance in checking the clearances, etc.) that all you can expect to verify is that the cam timing is "close". Realistically, you can probably get as "close" by lining up the cams on the old factory marks. The most accurate way to set the cam timing is using "intake centerlines". For your 250 cams, they are 109 degrees ATDC. Use cylinders #1 and #7. I would first set the cams on the "factory marks", then turn the flywheel to 109 degrees after top dead center. From that point, you can take the cam sprocket bolts out and carefully rotate the camshaft to the point of "highest intake lift". You can measure this with a dial indicator. It should be very close to the "factory marks". This method takes most of the variables out of the equation and should provide the most accurate "overall" setting. I have only provided a quick summary of this process, so be careful and be thoughtful as you work.
     
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  10. christc

    christc Formula Junior

    Mar 3, 2013
    312
    Germany
    Thanks Dyke for the answer and very accurate description. Thats how I will do it.

    Thanks
    Christopher
     
  11. lancia

    lancia Formula Junior

    Jan 18, 2004
    368
    Hi Dyke, If I may a related tool set up question. Do you use a degree wheel fastened off the front nose of the crankshaft and a pointer set up off the timing case? Most degree wheels, if not all, appear configured to work off the front. OR, do you prefer exactly centering and clamping a degree wheel to the flywheel face after establishing true TDC for easier direct comparison to the factory flywheel marks?. (If you use the flywheel end, you have to ignore the the ATDC, etc range markings on most degree wheels offered, because the rotation is opposite from the nose application.) 250GT and 275GT flywheels are a fraction larger in diameter than 11". For example Summit Racing offers several degree wheels that are 11" diameter and would fit the flywheel with markings near the circumference. Hope I am making sense and apologies if I misunderstand or am missing the obvious. Thanks, Chris
     
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  13. turbo-joe

    turbo-joe F1 Veteran

    Apr 6, 2008
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    romano schwabel
    it does not matter when you can count a little if the degree wheel will be clockwise or anticlockwise
     
  14. lancia

    lancia Formula Junior

    Jan 18, 2004
    368
    Yes, that is obvious and understood. I am simply asking if Dyke has a preferred method.
     
  15. DWR46

    DWR46 Formula 3
    Honorary

    Jun 19, 2012
    1,358
    Chris: If the engine is out of the car, we always mount the degree wheel on the flywheel. Luckily, Ferrari's have pretty accurately marked flywheels (if the car still has the original flywheel), so they are a fairly good indicator of what is happening for checking with the engine in the car. You can always calculate how many degrees per tooth and get fairly close using the factory flywheel.
     
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  16. lancia

    lancia Formula Junior

    Jan 18, 2004
    368
    Thank you Dyke, that seemed to me the best way to set up if the engine is out - advice appreciated, Chris
     
  17. christc

    christc Formula Junior

    Mar 3, 2013
    312
    Germany

    Attached Files:

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  18. lancia

    lancia Formula Junior

    Jan 18, 2004
    368
    Thank you Christopher, I see that you have two dial indicators set up, one per bank, efficient.
     
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  19. turbo-joe

    turbo-joe F1 Veteran

    Apr 6, 2008
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    romano schwabel
    and how many ° CS inlet and outlet valve are now open?
     
  20. christc

    christc Formula Junior

    Mar 3, 2013
    312
    Germany
    Here is what I got to using the setup:
    Right Bank:
    Intake Opens - Exactly 27 before TDC (target 27)
    Intake Close - 63.5 after BDC (target 65)
    Exhaust Opens - 73 before BDC (target 74)
    Exhaust closes - Exactly 16 after TDC (target 16)

    Left Bank:
    Intake Opens - 29 before TDC (target 27)
    Intake Close - exactly 65 after BDC (target 65)
    Exhaust Opens - exactly 74 before BDC (target 74)
    Exhaust closes - 13 after TDC (target 16)

    I feel thats as close as I will get.

    Christopher
     
  21. turbo-joe

    turbo-joe F1 Veteran

    Apr 6, 2008
    6,605
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    romano schwabel
    this is very close and OK for daily driving
    so you have then 270° camshafts?
    right bank inlet: 270,5 °
    right bank outlet: 270°
    left bank inlet: 274°
    left bank outlet: 267°
    right bank seems ok for me
    left bank intake I think a little less valve clearance and exhaust a little too much? so I count in 1/100 mm ;)
    so you have been absolutely right with adjusting the timing with the correct valve clearance. all day learning something new :)
     

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