All 1975 and later Novas are equipped with an underfloor catalytic converter. This mufflerlike appearing device is attached to the exhaust pipe(s) coming from the exhaust manifold(s). The converter housing is of a three-layer construction. The outer layer is an aluminized steel cover with a ceramic felt insulating blanket beneath. The main structure (converter shell) is below the blanket and is made of stainless steel as are the exhaust pipes forward of the converter.
Inside the housing are pellets which contain the catalyst agent. The pellets are made of a ceramic material and are impregnated with platinum and palladium. These "noble" metals contain the catalyst agent. The total amount of catalyst agent in the converter is 0.05 Troy ounces (0.36 grams).
The catalyst agent remains effective in converting exhaust gases (hydrocarbons and carbon monoxide) into carbon dioxide and water only as long as it is exposed to the gases. It is for this reason that unleaded fuel only must be used. Lead in leaded fuel is not consumed in the combustion process and enters the converter where it attaches itself to the ceramic pellets. When the catalyst agent becomes coated, the converter becomes useless for emission control. If necessary, the catalyst in a converter can be replaced.