Ignition Timing

Ensure engine is warmed up to normal operating temperature, A/C is turned off and transmission is in "Neutral". Connect timing light to either No. 1 or No. 4 cylinder.
On Impulse models, throttle valve must be completely closed and idle contact on. Harness of pressure regulator vacuum switching valve must be disconnected.
On all models, loosen distributor clamping bolts and turn distributor in either direction until timing is within specifications. See Fig 1 .

Fig 1: Isuzu Timing Mark Location (Adjust Ignition Timing With Engine At Proper Idle RPM)

IGNITION TIMING (DEGREES BTDC @ RPM)

Application	Setting
Impulse	12° @ 900