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 MANUALSCHEVROLET1987SUBURBAN R20, 7.4 N, 400/M40REPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMCARBURETOR - ROCHESTER M4ME & M4MEF 4-BBLOVERHAULDISASSEMBLYTHROTTLE BODY
1987 Chevrolet Suburban R20, 7.4 N, 400/M40
Throttle Body
1987 Chevrolet Suburban R20, 7.4 N, 400/M40SECTION Throttle Body
- Remove accelerator pump rod from throttle lever by rotating rod until tang on rod aligns with slot in lever. Place carburetor in holding fixture, manifold side up, to prevent damage to throttle valves.
- Using a hacksaw, make 2 parallel cuts in throttle body, one on each side of locator point. See Fig 1. Cuts should be down to plug, but must not extend more than 1/8" past locator points.
- Place a small, flat punch at a point near end of saw marks. Hold punch at a 45 degree angle and drive into throttle body until casting breaks away. Plug should be exposed.
- Hold a center punch vertically and drive into plug. Change punch angle to 45 degrees and drive plug out of casting. Plug will shatter. It is not necessary to remove plug completely, only enough to allow access to idle mixture screw.
- Count number of turns required to lightly seat idle mixture screws and record for reassembly reference. Remove idle mixture screws. DO NOT disassemble throttle body. Throttle body is serviced as a complete assembly.
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.