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Carburetor - Carburetor work - Carburetor theory - Carburetor basics - Carburetor Catalytic - Carburetor fuel supply - Carburetor parts - Carburetor supersession - Carburetor variable venturi - Carburetor adjustment - Carburetor barrels

Carburetor Adjustment

Two-Needle Carburetor Assembly

Ways to check carburetor mixture adjustment include: measuring the carbon monoxide, hydrocarbon, and oxygen content of the exhaust using a gas analyzer, or directly viewing the color of the flame in the combustion chamber through a special glass-bodied spark plug sold under the name "Color tune" for this purpose. The flame color of stoichiometric burning is described as a "Bunsen blue", turning to yellow if the mixture is rich and whitish-blue if too lean.

The mixture can also be judged after engine running by the state and color of the spark plugs: black, dry sooty plugs indicate a too rich mixture, white to light gray deposits on the plugs indicate a lean mixture. The correct color should be a brownish gray.

In the early 1980s, many American-market vehicles used special "feedback" carburetors that could change the base mixture in response to signals from an exhaust gas Oxygen sensor. These were mainly used to save costs (since they worked well enough to meet 1980s emissions requirements and were based on existing carburetor designs), but eventually disappeared as falling hardware prices and tighter emissions standards made fuel injection a standard item.

Where multiple carburetors are used the mechanical linkage of their throttles must additionally be adjusted to synchronism for smooth engine running.

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Carburetor - Carburetor work - Carburetor theory - Carburetor basics - Carburetor Catalytic - Carburetor fuel supply - Carburetor parts - Carburetor supersession - Carburetor variable venturi - Carburetor adjustment - Carburetor barrels