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, 4.8 T, AUTOMATIC, 475/M40REPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMCARBURETOR - ROCHESTER M4M SERIES 4-BBLADJUSTMENTSSECONDARY THROTTLE VALVE LOCK-OUTLOCK-OUT LEVER OPENING CLEARANCE
1985 Chevrolet Step Van P20, 4.8 T, Automatic, 475/M40
Lock-Out Lever Opening Clearance
1985 Chevrolet Step Van P20, 4.8 T, Automatic, 475/M40SECTION Lock-Out Lever Opening Clearance
- Push down on tail of fast idle cam to completely open choke valve.
- Measure secondary throttle valve lock-out lever opening clearance between end of pin and toe of lock-out lever. See Fig 1.
- File end of lock-out pin to obtain clearance of .015". Make sure all burrs are removed.
NOTE:
Both steps must be done to perform adjustment.
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.