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 MANUALSCHEVROLET1985C 30 P/U 2WD L6-292 4.8LREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTIGNITION SYSTEMIGNITION TIMINGADJUSTMENTS
1985 Chevrolet C 30 P/U 2WD L6-292 4.8L
Ignition Timing: Adjustments
1985 Chevrolet C 30 P/U 2WD L6-292 4.8LSECTION Adjustments
Set timing at slow idle and Before Top Dead Center, unless otherwise specified.
2.5L (151), ground diagnostic connector under dash. Average pulses of cylinders 1 & 4.
2.8L (173) FI, place system in bypass mode, disconnect tan/black wire by ECM in passenger compartment.
2.8L (173) 2V EST, disconnect 4-wire connector at distributor.
4.3L (262) FI, place system in bypass mode, disconnect tan/black wire at distributor.
All V8 W/FI, place system in bypass mode, disconnect tan/black wire inboard of bulkhead.
All others, disconnect & plug distributor vacuum hoses(s).
RENDER: 1.0x
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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.