Heat Risers?
Elder User
Joined: Apr 2004
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It is a damper valve which closes the outlet on one bank to direct the hot exhaust thruthe intake manifold passsage under the carb heating the intake to provide better
carburation while the engine is cold. The valve is closed by a bimetal spring which then relaxes when warm to allow normal passage of the gases out the pipe. One problem does exsist with the idea, the passage thru the manifolds carbon shut and the system becomes ineffective. The valves frequently bind upon the shaft, solvents and
some work can free them. Sometimes the damper valve plate will break off the shaft.
Later designs used vacuum motors to activate the valve.
carburation while the engine is cold. The valve is closed by a bimetal spring which then relaxes when warm to allow normal passage of the gases out the pipe. One problem does exsist with the idea, the passage thru the manifolds carbon shut and the system becomes ineffective. The valves frequently bind upon the shaft, solvents and
some work can free them. Sometimes the damper valve plate will break off the shaft.
Later designs used vacuum motors to activate the valve.
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