Chevrolet Full-size Cars 1968-1978 Repair Guide

Intake Manifold

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REMOVAL & INSTALLATION



Inline 6-Cylinder Engines

The 1975-78 engines are equipped with an intake manifold which is integral with the cylinder head and must be removed along with the cylinder head.

  1. Disconnect the negative battery cable. Remove the air cleaner.
  2.  
  3. Disconnect the throttle rods at the bellcrank and remove the throttle return spring.
  4.  
  5. Disconnect and plug the fuel line at the carburetor. Disconnect the vacuum lines at the carburetor.
  6.  
  7. Disconnect the crankcase ventilation hose from the valve cover and the evaporation control hose from the carbon canister.
  8.  
  9. Disconnect the exhaust pipe from the manifold and throw away the packing.
  10.  
  11. Remove the manifold assembly and scrape off the gaskets.
  12.  
  13. Check the condition of the manifold. If a manifold is cracked or distorted 0.030 in. or more, it should be replaced to prevent exhaust leakage. To detect distortion, lay a straightedge along the length of the exhaust port faces. If, at any point, a gap of 0.030 in. or more exists between the straightedge and the manifold, distortion of that amount is present.
  14.  
  15. Be removing one bolt and two nuts, the manifold can be separated.
  16.  

To install:

  1. Position the manifold assembly to the cylinder block. Be sure to use new gaskets. Install the retaining bolts. Install the exhaust pipe, as required.
  2.  

The center and end bolts torque different.

  1. Install the PCV valve hose and the evaporation control hose. Connect the fuel line. Connect the vacuum lines.
  2.  
  3. Connect the throttle rods at the bellcrank. Connect the throttle return spring.
  4.  
  5. Install the air cleaner. Connect the negative battery cable. Start the engine and check for leaks, correct as required.
  6.  

All V8 Engines


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Fig. Fig. 1 Intake manifold torque sequence for small block Chevrolet engines



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Fig. Fig. 2 Intake manifold torque sequence for big block Chevrolet engines



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Fig. Fig. 3 Label and disconnect any vacuum hoses that are connected to the intake manifold



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Fig. Fig. 4 Disconnect the upper radiator, and heater hoses from the engine. Remove the distributor



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Fig. Fig. 5 Detach the throttle lever cables, then unfasten the throttle cable bracket to the intake manifold ...



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Fig. Fig. 6 ... and position it out of the way. Unfasten the power brake vacuum line from the carburetor



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Fig. Fig. 7 Loosen and remove any brackets or ...



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Fig. Fig. 8 ... support rods bolted to the manifold. Remove any remaining intake manifold attaching bolts



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Fig. Fig. 9 Gently pry on the intake manifold to break it free, then lift the manifold off of the engine



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Fig. Fig. 10 Stuff rags into the intake ports in the cylinder heads and ...



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Fig. Fig. 11 ... cover the lifter valley before scraping off the old gaskets. This will keep dirt out of the engine

  1. Remove the air cleaner.
  2.  
  3. Drain the radiator.
  4.  


CAUTION
When draining engine coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain coolant into a sealable container. Coolant should be reused unless it is contaminated or is several years old.

  1. Disconnect:
  2.  
    1. Negative battery cable.
    2.  
    3. Upper radiator and heater hoses at the manifold.
    4.  
    5. Crankcase ventilation hoses as required.
    6.  
    7. Fuel line at the carburetor.
    8.  
    9. Accelerator linkage and TV cables, if equipped.
    10.  
    11. Vacuum hose at the distributor, if equipped.
    12.  
    13. Power brake hose at the carburetor base or manifold, if applicable.
    14.  
    15. Ignition coil, the spark plug wires and temperature sending switch wires.
    16.  
    17. Water pump bypass at the water pump (Mark IV engine only).
    18.  

  3. Remove the distributor cap and scribe the rotor position relative to the distributor body.
  4.  
  5. Remove the distributor.
  6.  
  7. If applicable, remove the alternator upper bracket. As required, remove the oil filler bracket, air cleaner bracket, air conditioning compressor and bracket, and accelerator bellcrank.
  8.  
  9. Remove the manifold-to-head attaching bolts, then remove the manifold and carburetor or throttle body as an assembly.
  10.  
  11. If the manifold is to be replaced, transfer the carburetor (and mounting studs), water outlet and thermostat (use a new gasket) heater hose adapter, EGR valve (use new gasket) and, if applicable, TVS switch and the choke coil. 1975-78 engines use a new carburetor heat choke tube which must be transferred to a new manifold.
  12.  
  13. Using a gasket scraper clean the gasket and seal surfaces of the cylinder heads and manifold.
  14.  

To install:

  1. Install the manifold end seals, folding the tabs if applicable, and the manifold/head gaskets, using a sealing compound around the water passages.
  2.  

1974-75 V8 engines require a new intake manifold side gasket on 4-bbl engines. The new gasket has restricted crossover ports. The 350 2-bbl uses a restricted crossover gasket on the right-hand side and an open gasket on the left. The 350 4-bbl uses restricted crossover gaskets on both sides. The correct gaskets are essential.

  1. When installing the manifold, care should be taken not to dislocate the end seals. It is helpful to use a pilot in the distributor opening. Tighten the manifold bolts to 30-35 ft. lbs. in the sequence illustrated.
  2.  
  3. If applicable, install the alternator upper bracket. As required, install the oil filler bracket, air cleaner bracket, air conditioning compressor and bracket, and accelerator bellcrank.
  4.  
  5. Install the distributor.
  6.  
  7. Install the distributor cap and scribe the rotor position relative to the distributor body.
  8.  
  9. Connect:
  10.  
    1. Negative battery cable.
    2.  
    3. Upper radiator and heater hoses at the manifold.
    4.  
    5. Crankcase ventilation hoses as required.
    6.  
    7. Fuel line at the carburetor.
    8.  
    9. Accelerator linkage and TV cables, if equipped.
    10.  
    11. Vacuum hose at the distributor, if equipped.
    12.  
    13. Power brake hose at the carburetor base or manifold, if applicable.
    14.  
    15. Ignition coil, the spark plug wires and temperature sending switch wires.
    16.  
    17. Water pump bypass at the water pump (Mark IV only).
    18.  

  11. Install the air cleaner. </