Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET1985IMPALA 4.3 Z, 700R4/MD8REPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMFUEL INJECTION SYSTEM - DIESELADJUSTMENTSINJECTION TIMINGCHECKING
1985 Chevrolet Impala 4.3 Z, 700R4/MD8
Injection Timing: Checking
1985 Chevrolet Impala 4.3 Z, 700R4/MD8SECTION Checking
- 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.
- 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.
- 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.
- 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).
- 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.
- 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.
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.