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Home >> Chevrolet >> 1985 >> Impala 5.0 H >> Repair and Diagnosis >> Engine Performance >> System >> Fuel Injection System - Diesel >> Adjustments >> Injection Timing >> Checking
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Injection Timing: Checking

  1. Engine must be at normal operating temperature. Place transmission selector lever in "P". Remove air cleaner and install Cover (J-26996-1). Remove MAP sensor retainer. Disconnect EGR valve hose.
  2. Clean engine probe holder (RPM counter) and crankshaft balancer rim. Clean lens on both sides of glow plug probe. Clean lens in the photo-electric pick-up.
  3. Use a dull toothpick to scrape the carbon from the combustion chamber side of glow plug probe. Retarded readings will result if probe is not clean.
  4. Install RPM probe into crankshaft RPM counter (probe holder). Remove glow plug from No. 3 cylinder on a V8 or No. 1 on a V6. Install glow plug probe in glow plug opening. Tighten probe to 8 ft. lbs. (11 N.m).
  5. On V8 engine, set timing meter offset selector to B (99.5). On V6 engine, set selector to A (20). Connect battery leads. Unplug alternator 2-lead connector.
  6. If alternator lead is difficult to remove, remove gauge fuse when engine is not running. Start engine. Check injection timing. See Injection Pump Timing Specifications.
INJECTION PUMP TIMING SPECIFICATIONS

Application Degrees ATDC @ RPM
V6
"A" Series 6@1300
"G" Series 5@1300
V8 4@1250
CAUTION: Anything that affects fuel pressure to the injection pump will change timing. If pump timing is adjusted, and later fuel system is found to be restricted, timing may be incorrect.