The DB2 housing cover is easily...
The DB2 housing cover is easily removed for service and modifications, even when the pump is still on the engine.
GM models that were '81-and-later also were equipped with a housing pressure cold advance solenoid. It consisted of a solenoid assembly in the governor cover and a ball-check fitting. The unit allows more advance at cranking and engine warm-up by reducing housing pressure, which allows the power piston to move further (approximately three degrees) in the advance direction. This results in a slower, more complete burn of the fuel.
The min-max governor regulates the injection pump at low idle and maximum-rated speeds. At speeds between these two ranges, the throttle lever and governor spring directly control the metering valve.
The DB2 can be timed in a...
The DB2 can be timed in a similar fashion to a gas engine using a special Stanadyne Time Trac strobe light.
The governor assembly consists of a cage with flyweights mounted on the rotor and a system of linkages. The movement of the weights acting against the governor thrust sleeve rotates the metering valve by means of the governor arm and linkage hook. The amount of rotation varies the position of the metering valve, thereby controlling the amount of fuel to the pumping plunger. The governor derives its energy from the weights pivoting in the weight retainer. Centrifugal force throws the weights outward, moving the thrust sleeve against the governor arm and rotating the metering valve through a simple, positive linkage.
Retention of heat is a critical factor in fuel thinning after a high-ambient heat soak. As the hotter, thinner fuel passes through the pump, internal leakage increases and reduces fuel output. To compensate for this loss, a bimetallic temperature compensator strip was added to the governor arm to increase the metering valve opening. This provides a compensated idle speed curve and corrects engine idle speed at elevated ambient temperature.
A sensor that comes with the...
A sensor that comes with the Time Trac measures vibrations from the number one cylinder fuel line. It senses the injection fuel pulse and illuminates the timing light.
The metering valve allows a varying amount of fuel to pass through the charging passage to fill the pumping plungers in the distributor rotor. As the rotor revolves, the inlet passage registers with the charging ports in the hydraulic head, allowing fuel to flow into the pumping plunger. With further rotation, the inlet passages move out of registration and the discharge port of the rotor registers with another head outlet. While the discharge port is open, the rollers contact the cam lobes and force the plungers together. Fuel trapped between the plungers is then pressurized and delivered through the delivery valve (and the injectors) to the combustion chamber.
The DB2 is near the end of its production cycle, being replaced by electronic-controlled diesels. For many enthusiasts, this pump was on their first diesel, and there are still thousands of them in use in Ford and GM trucks.
Stanadyne DB2 Injection Pump Specs
* Rated for up to 25 hp per engine cylinder
* Peak injection pressures to 6,700 psi* 2-, 3-, 4-, 5-, 6-, and 8-cylinder configurations
* All-speed governor
* Built-in automatic advance
* Electric shut-off
* Handles engine speeds to 5,000 RPM