GxT Ferret 88 Timing Light - Manual (Page 3)

Initial Timing Measurement
Follow the engine service manual procedure or the emission control label in the
engine compartment. Not all engines can be adjusted. For engines with fi xed
timing, you can determine the operational status of the timing system.
Vacuum Advance or Retard Measurement
Vacuum actuators connected to the distributor or intake manifold sensors vary
the timing according to engine vacuum. To measure, disconnect and plug the
input hoses and then couple the input to a hand pump with gauge. Run the
engine at idle to see the timing change with and without applied vacuum.
Centrifugal Advance Measurement
Mechanical ignition controls usually have a set of spinning weights in the
distributor which advance the spark timing a certain number of degrees as RPM
goes from idle to driving range. To see the centrifugal advance alone, vacuum
actuators must be disabled. Besides the amount of change, it is important to see
that the advance changes smoothly with slowly increasing RPM. Sticky weight
pivots, rust, and bad retracting springs are the usual problems.
Total Advance Measurement
This is the advance at a specifi ed RPM with the engine timing controls intact.
Coil Wire Timing
Use only when required by engine specifi cations. Be sure to set advance to
zero, because the location of the mark will otherwise be affected by the number
of cylinders.
Inductive Pickup
around Spark Wire
Timing Advance
Control Buttons
Timing Marks