Fits All 320 Engines - Century, Roadmaster, Limited
Cast Iron / Machined as Original
Does not have "butterfly"
Originally, Buick incorporated a “butterfly” or “flapper” in its valve bodies. Its purpose was to quickly heat the fuel mixture in the motor, particularly in cold weather. The butterfly valve is normally closed when the engine is cold. In its closed position, exhaust gas would be directed into the intake manifold, heating the fuel mixture and the surrounding area. As the engine and valve body warms, a heat sensitive spring on the side of the valve body would allow the butterfly to open, directing exhaust gas into the exhaust pipe and exiting the vehicle. The valve required regular maintenance as it often seized. If it happened to seize in the closed position, the exhaust gas would continue to heat the fuel mixture and the intake manifold, often causing poor performance, vapor lock and engine damage. Many a Buick restorer remembers having had to “hammer” the valve back and forth to get it to temporarily function. Because our cars are now used primarily for warm weather use and the need for quicker “warm ups” is not necessary, we eliminated the butterfly valve. We also eliminated the need for continual maintenance, poor performance and the possibility of engine damage due to a stuck valve
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