PEUGEOT Engine Modification: Description

Peugeot 304 and 504 exhaust emission control system components consists of:

1. Model 504 uses two carburetors, a 32 BICSA 2 and a 34 PBIC 8. This 304 uses a 34 PBISA 4 carburetor. These carburetors are equipped with a device on throttle control which will position throttle in two positions, slow idle of 800 RPM, or fast idle of 1300 RPM (304), 1400 RPM (504).
   NOTE: On dual carburetor system, only the 32 BICSA 2 has this device.
2. A vacuum diaphragm unit connected to accelerator by an adjustable rod.
3. On 304 a vacuum connection which controls the vacuum ignition advance limiter.
4. A three-way electro vacuum control valve, which controls diaphragm unit with either intake manifold vacuum or normal atmospheric pressure.
5. A sensing head mounted on rear of transmission of 504 and in differential housing of 304, which controls operation of electro vacuum valve, up to 22 MPH (304), 25 MPH (504) with speed increasing and from 19 MPH (304), 22 MPH (504) with speed decreasing.
6. On 504 a vacuum damper in tube between vacuum unit and electro vacuum control, which slows down vacuum, enabling progressive operation of fast idle and return to normal idling.
7. 504 has two idling electro valves which shut off idling jets when ignition is turned off.
   Fig 1: Peugeot 504 Coppolair System (Typical)

   Courtesy of PEUGEOT MOTORS OF AMERICA, INC.
   Fig 2: Peugeot 304 Heated Air System

   Courtesy of PEUGEOT MOTORS OF AMERICA, INC.
8. On 304 a heater box is attached to exhaust pipe and is linked to an air intake tube by a duct. An expanding wax thermostatic element is attached to air filter cover. This element opens or closes a flap (through a cable) which is located in air intake tube.
9. On 504 a heater box is attached to exhaust pipe and is linked to a mixing box which is attached to air intake of engine. Metering of hot and cold air is accomplished by a flap in mixing box. This flap is controlled by a wax thermostatic element.