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Bought advanced timing light - should it measure advance ?

Discussion in 'Bay Tech Clinic' started by VaiseW, Jun 16, 2021.

  1. Doob

    Doob Member

    Messages:
    49
    Location:
    Perth
    With regard to the advance timing feature of the timing light.
    I also have an Equus 590 518 timing light. I believe the Advance feature can be used to check ignition timing advance at various engine rpm without requiring a graduated crank shaft pulley.
    If, for example, the desired idle ignition timing is say 7.5 deg BTDC, then with the 'Advance' setting on the timing light set at zero, the distributor is rotated until the timing strobe light shows the pulley 7.5 deg BTDC marking aligned with the crank case join. At this point the strobe light will show the TDC dimple marking on the pulley to be approximately 12mm to the left of the crank case join. To check the timing, adjust the "Advance" angle on the strobe light until the TDC dimple marking on the pulley aligns with the crank case join. This should occur when the timing light Advance is set at 7 or 8 deg.
    Similarly, if you wanted to check the timing advance at say 1500 rpm - with the 'Advance' setting on the timing light set at zero, the strobe light will show the TDC dimple marking on the pulley to be much further (say for example approx 32 mm) to the left of the crank case join. Then holding 1500 rpm adjust the 'Advance' setting on the timing light until the strobe light once again shows the TDC dimple marking on the pulley aligning with the crank case join. This might be say 20 deg 'Advance' (BTDC) as indicated by the timing light.
    So I guess the 'Advance' feature of the timing light allows the user to delay/retard the strobe light flash by a specified angle, to bring the TDC dimple marking on the pulley in alignment with the crank case join - and thus measure the BTDC timing.
    Please correct me if I am wrong in my interpretation of this 'Advance' feature of the timing light.
     
    Mordred likes this.
  2. Mordred

    Mordred Super Moderator Staff Member

    Messages:
    3,005
    Location:
    Penna, Hobart
    That sounds like what it does exactly. I was wondering how it was picking up a signal or pulse from somewhere and doing a calculation, but advancing or retarding the strobe flash to allow you to align on a TDC mark by a defined amount makes much more sense. I picked up a similar unit a few weeks back, mainly to replace a few pieces of equipment with one, but wasn't too worried about this additional feature.

    I might just add that you don't use the crankcase join usually on a Type IV engine (its behind the fan shroud and the marks on the pulley aren't cut in the same place as a result), but standard practice on a Type 1.

    Adrian
     
    Doob and oldman like this.
  3. Doob

    Doob Member

    Messages:
    49
    Location:
    Perth
    Yes, good point Adrian - I should have been more general/generic with regard to alignment of the TDC timing marks. Guess I was just focused on my Type 1 motor, and the fun I have had trying to check if the mechanical and vacuum advance are working as to be expected.
     
    Last edited: Sep 9, 2021
  4. Mordred

    Mordred Super Moderator Staff Member

    Messages:
    3,005
    Location:
    Penna, Hobart
    Me too. After a lot of fiddling I think they are in the ball park.

    Cheers

    Adrian
     

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