The Detroit Diesel Series 71 fuel injector (Part #5228770) is a mechanical unit injector (MUI), a key component in Detroit Diesel’s two-stroke engines. Here’s a breakdown of its structural characteristics:

1. Main Components:

• Injector Body — Heavy-duty steel housing designed to withstand high-pressure fuel delivery.

• Plunger & Barrel Assembly — Precision-machined components that generate injection pressure (up to ~3,000 psi).

• Nozzle & Tip — Features small spray holes (orifices) for atomizing fuel into the combustion chamber.

• Spring & Check Valve — Controls fuel flow and ensures proper injection timing.

• Adjusting Screw — Allows calibration of injection pressure (critical for performance).

2. Key Design Features:

• Integrated Design — Combines fuel pumping and injection in a single unit (no separate fuel lines).

• Mechanical Actuation — Driven by the engine’s camshaft (no electronic controls, typical of older Detroit Diesel engines).

• Self-Lubricating — Uses diesel fuel for internal lubrication.

• Sealing & Gaskets — Includes copper washers and O-rings to prevent leaks.

3. Functional Characteristics:

• Direct Injection — Sprays fuel directly into the cylinder (no pre-combustion chamber).

• Timing Adjustable — Injection onset can be fine-tuned via shims or screw adjustments.

• Pop-Off Pressure — Typically set between 1,800–3,000 psi (varies by engine model).