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 MANUALSCHEVROLET1985STEP VAN P20, 6.2 J, AUTOMATIC, 475/M40REPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCEADJUSTMENTTUNE-UP - V8TESTINGENGINE COMPRESSION
1985 Chevrolet Step Van P20, 6.2 J, Automatic, 475/M40
Engine Compression
1985 Chevrolet Step Van P20, 6.2 J, Automatic, 475/M40SECTION Engine Compression
When making compression checks, disconnect ignition switch connector Pink wire from high energy ignition system. With air cleaner removed and throttle and choke wide open, crank engine through at least 4 compression strokes.
COMPRESSION SPECIFICATIONS
| Application | Specification | ||||
|---|---|---|---|---|---|
| Compression Ratio | |||||
| 5.0L | |||||
| Federal | 9.2:1 | ||||
| Calif. | 8.6:1 | ||||
| 5.7L | |||||
| Light Duty | 8.2:1 | ||||
| Heavy Duty | 8.3:1 | ||||
| 7.4L | 8.0:1 | ||||
| Compression Pressure | 150 psi (10.5 kg/cm2 ) | ||||
| Maximum Pressure Variation | (1) 30% | ||||
|
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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.