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Intake Manifold

Intake Manifolds, or Inlet Manifolds, supply the cylinders of an engine with fuel and air mixtures. The flow of air or air-fuel mixture from the throttle body to the cylinder head. The throttle body feeds the plenum chamber, which then feeds individual tubes, called runners, to each intake port.

  • The intake manifold is also a set of tubes. These tubes carry air or fuel mixture from the throttle valves to the intake ports in the cylinder head. 
  • On in-line engines, the intake manifold attaches to the side of the cylinder head. On V-types of engines,  the intake manifold is located in between the two banks of cylinders. Some in-line engines have the intake and exhaust manifolds on the same side of the cylinder head. Other engines have manifolds on opposite sides.

Exhaust manifolds for some carbureted in-line engines have a heat control valve. It helps provide heat to the air-fuel mixture in the intake manifold while the engine is cold. This improves the fuel vaporization for better cold engine performance. Some V-type engines have an exhaust gas passage that runs across the intake manifold under the carburetor mounting pad. 

  • When the engine is cold, the heat-control valve forces the exhaust gas from one cylinder bank through the passage, This enables to heat the air fuel mixture entering the intake manifold.