Chevrolet Corvette 1963 Repair & Tune-Up Manual page 53

48 TUNE-UP AND PERFORMANCE MAINTENANCE
1982 EST BYPASS wire connector location. On these models, this connector must be separated prior to
setting the ignition timing—see text
NOT use a timing light which requires pierc-
ing of the spark plug lead. Timing lights which
have a lead that must be installed between
the plug and the plug wire may be used with
conventional ignition systems. On HEI igni-
tion systems, use ONLY an inductive pickup-
type timing light.
NOTE: Timing lights requiring a 12 volt
DC power source (battery) may be con-
nected as follows: Connect the positive tim-
ing light lead to the BAT terminal of the
alternator; the negative timing light lead to
a good engine ground. CAUTION: Be
careful not to ground the positive lead to
the alternator case.
4. Locate the timing tab (metal tab marked
in graduations) which is attached to the tim
ing cover. Locate the single mark on the vi
bration damper (one groove). Clean both the
timing tab and the damper marking. Use chalk
to accentuate the marks if necessary.
5. Be sure that all wiring and tools are clear
of the fan and belts. Start the engine and al
low it to idle. Aim die timing light at the
marks and note where the vibration damper
mark aligns with die timing tab.
NOTE: The "O" marking on the tab is the
top dead center (TDC) mark and all the be-
fore top dead center (BTDC) marks are on
the "before" (advance] sice of the zero, or
the "A" (advance] side of zero. Later models
are marked to indicate Before and After.
6. Loosen the distributor clamp (hold-
down) bolt and slowly rotate the distributor
as necessary until the damper mark is aligned
with the specified mark of the timing tab.
Tighten the hold-down bolt and recheck the
timing.
7. Turn the engine off and remove the
timing light.
8. If so equipped, unplug and reconnect
the vacuum advance hose to the distributor.
7980 CALIFORNIA
Refer to the underhood emissions label for
the proper timing adjustment procedure.
1981
Refer to the underhood emissions label for
the proper timing adjustment procedure.
7982-84
The ignition timing of 1982-84 models is ad-
justed in basically the same manner as pre-
viously described (1963-80). The exception
to this is that the EST BYPASS wire from the
distributor must be disconnected prior to the
timing adjustment. Trace the four wires from