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Home >> GMC >> 1973 >> Jimmy 5.7L Eng, Not Available Trans, _NA_ >> Repair and Diagnosis >> Engine Performance >> Ignition System >> Tune-Up - V8 >> Ignition Timing

Ignition Timing

Ignition timing is checked or adjusted with engine at normal operating temperature, distributor vacuum line disconnected and plugged, transmission in Neutral and engine at normal idle.

Ignition Timing Specifications

Application Man. Trans. Auto. Trans.
307"
  Light Duty 4° BTDC 8° BTDC
  Heavy Duty TDC TDC
350"
  Light Duty 8° BTDC 12° BTDC
  Heavy Duty 4° BTDC 4° BTDC
454"
  Light Duty 10° BTDC 10° BTDC
  H/D (Federal) 10° BTDC 10° BTDC
  H/D (Calif.) 5° BTDC 8° BTDC