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 MANUALSCHEVROLET1983CHEVY VAN G30, 5.7 M, 475/M40REPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMCARBURETOR - ROCHESTER M4MC & M4ME 4-BBLOVERHAULDISASSEMBLYTHROTTLE BODY
1983 Chevrolet Chevy Van G30, 5.7 M, 475/M40
Throttle Body
1983 Chevrolet Chevy Van G30, 5.7 M, 475/M40SECTION Throttle Body
- Remove accelerator pump rod from throttle lever by rotating rod until tang on rod aligns with slot in lever.
- It is not necessary to disassemble throttle body any further. DO NOT remove idle mixture screw plugs unless it is necessary to replace mixture screws or cleaning and air pressure fails to clean idle mixture passages.
- If necessary to remove idle mixture plugs, proceed as follows: Invert throttle body and position on a holding fixture with manifold side up. Position a punch in between 2 locator points on manifold side of throttle body. There are 2 locator points adjacent to each mixture screw.
- Using a hammer, drive punch against throttle body to break out portion of throttle body to gain access to idle mixture screw plugs. Drive out hardened steel plugs.
- Hardened steel plugs will shatter. It is not necessary to remove plug completely. Remove just enough pieces to allow idle mixture adjusting tool (J-28706) or a thin-walled 3/16" deep socket to be used to remove mixture screws and spring.
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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.