Start and run engine at idle speed.
WARNING: Due to the stopping or freezing action of the light flash, care must
be taken to avoid touching the engine fan blade or other moving parts while
the engine is running. Action of the light will cause these parts to appear
to slow down and/or stop while they are still in rapid motion.
Direct flash from timing light onto engine timing marks. See Fig. 1 and
note the degree value indicated by the timing mark.
Loosen distributor locking screw and rotate distributor body left or right
until timing marks appear to correspond with manufacturer's specifications.
Tighten distributor locking screw, recheck timing - if OK stop engine. If
not, reset timing.
If you do not proceed with test outlined below, remove timing light and
reconnect vacuum lines and replace timing light in case if timing oper-
ation is completed.
NOTE: After timing engine, the timing light may be used to check operation of
the distributor advance machanism as outlined in the following steps. On some
late model cars, certain emission control systems will prevent this check from
being performed since advance is dependent upon transmission speed or gear
used, or upon engine temperature. Check your manufacturer's shop manual for
proper procedures to use for these cars.
5. With timing light connected as for timing procedure, start and run engine
at normal idle speed.
Gradually increase engine speed while observing timing mark. Timing mark
should appear to remain stationary until the automatic advance mechanism
cuts in. From this point on, the timing mark will appear to move gradu-
ally as engine speed is increased. If timing mark remains stationary, or
if movement is in short, sharp jerks, the automatic advance mechanism may
be sticking and should be repaired or replaced.
Connect vacuum line to distributor vacuum advance fitting. Open and close
throttle suddenly to cause rapid increase/decrease in engine speed while
observing timing mark.
If mark disappears or moves rapidly away from stationary mark, vacuum
advance is operating normally.
If mark remains stationary, vacuum advance is defective and should be
repaired or replaced.
Remove timing light and place in case.
8. Stop engine.