Detroit Diesel 3-71 Non-Turbo (4-Valve Head Type) – Injector Parts Catalog

The Detroit Diesel 3-71 Non-Turbo engine, known for its rugged reliability and consistent power delivery, is part of the legendary Series 71 family — a line that has powered countless industrial, marine, and generator applications since the 1930s. The 3-71 features three cylinders and a two-stroke configuration, producing dependable torque at low RPMs while maintaining efficiency under heavy-duty conditions. Maintaining the integrity of this engine’s fuel injection system is vital to preserving its signature performance, which is why Diesel Pro Power offers a complete selection of injector parts, tools, and accessories—all tested, warrantied, and ready for immediate worldwide shipping.

With over 40,000 satisfied customers globally, Diesel Pro Power has become the trusted name for authentic, remanufactured, and new Detroit Diesel parts. Whether you’re restoring a vintage 3-71 power unit or maintaining a running fleet, this catalog section provides every component you need to keep your fuel system precise, efficient, and reliable.

Understanding the Fuel Injection System on the Detroit Diesel 3-71 Non-Turbo

The Detroit Diesel 3-71’s mechanical unit injector system is one of its most defining features. Each injector functions as both a pump and nozzle, delivering metered fuel directly into the combustion chamber under extremely high pressure. The injectors are actuated mechanically by the camshaft through rocker arms, ensuring fuel delivery is perfectly synchronized with piston movement.

A proper injector service or replacement can dramatically improve starting performance, reduce smoke, restore power, and improve fuel economy. Because of this, every injector and related part in this catalog meets or exceeds OEM specifications for pressure, flow rate, and atomization.

Rebuilt Injectors for Detroit Diesel 3-71 (4-Valve Head)

Detroit Diesel Injector N55 – Rebuilt

The N55 injector is a balanced choice for standard performance applications, ideal for generators and low-load equipment. Rebuilt to factory standards, each unit includes new precision-ground internal components, new seals, and calibration for consistent spray pattern and fuel pressure.
Sold with a refundable core deposit, each injector is fully tested for leakage, spray uniformity, and pop pressure consistency.

Detroit Diesel Injector N60 – Rebuilt

The N60 injector offers a moderate increase in fuel delivery, suitable for marine engines, light trucks, and small industrial applications requiring slightly more torque. Rebuilt with OEM-grade components, this injector maintains reliability while offering improved throttle response.

Detroit Diesel Injector N65 – Rebuilt

Designed for higher output versions of the 3-71, the N65 injector offers a balanced blend of efficiency and power. It’s frequently used in construction equipment and propulsion engines that need sustained high-load performance. Like all Diesel Pro Power rebuilt injectors, it is bench-tested under simulated operating conditions to ensure perfect fuel atomization.

Detroit Diesel Injector N70 – Rebuilt

The N70 injector represents the performance edge for naturally aspirated 3-71 engines. It delivers a higher fuel rate and is commonly used in applications where additional pulling power or acceleration is desired. This injector is fully remanufactured with new plungers, valves, and springs to restore like-new performance.

Essential Tools for Injector Calibration and Timing

Proper injector timing is critical to engine efficiency, power, and emissions. Even the best injectors won’t perform optimally if timing is off by just a few thousandths of an inch.

Injector Timing Tool (1.484)

This tool, designed for HV6, N65, and N80 injectors, ensures correct timing adjustment. Precision machining guarantees accurate injector height measurements during tune-up or rebuild procedures.

Injector Timing Tool (1.460)

Used with HV7, N45, N50, N55, N60, N70, and N90 injectors, this timing gauge helps ensure consistent injector synchronization across all cylinders, critical for balanced engine operation.

Injector Timing Tool (1.508)

This tool is commonly used on select industrial applications of the 3-71. Its 1.508-inch dimension is vital for achieving correct injector lash and lift.

By maintaining proper injector height, operators can prevent excessive smoke, hard starting, and poor idle—all common signs of improper injector adjustment.

Fuel Delivery Components and Connectors

The Detroit Diesel 3-71 relies on a network of fuel lines, connectors, and washers to deliver fuel from the injection pump to the injectors without leaks or pressure loss.

Fuel Pipe Connector

The fuel pipe connector provides a secure and leak-free junction between fuel lines. Diesel Pro Power offers the original-style connector compatible with Series 71 and 92 engines, built to resist vibration and corrosion.

Fuel Pipe Washer

Each injector uses two washers to ensure a tight seal at the fuel connector joint. Made from high-quality copper alloy for maximum resilience under heat and pressure.

Fuel Jumper Lines – Short & Long

Each 3-71 engine uses alternating short and long jumper lines to distribute fuel evenly across the injectors. Precision-bent to exact OEM dimensions, these lines are manufactured for perfect alignment and secure fitting, minimizing the risk of leaks and maintaining consistent fuel flow.

Injector Installation and Service Tools

Injector Fuel Line Socket

Designed to install and remove injector fuel lines on Detroit Diesel 53, 71, and 92 series engines. The specialized socket design ensures a secure grip on the line nut while preventing rounding or damage to the fittings. This professional-grade tool is a must-have for maintenance and overhaul work.

Injector Service Kit

Includes seals, O-rings, and gaskets needed for servicing or rebuilding Detroit Diesel injectors. This economical kit ensures all wearable components are replaced, helping restore injector efficiency.

Injector Bracket and Related Hardware

A sturdy injector bracket holds each injector securely in the cylinder head under high operating pressures. Diesel Pro Power offers new replacement brackets, bolts, and washers, all zinc-coated for corrosion protection.

Injector Internal Components

Injector Tips (Nozzle Ends)

Each injector tip determines spray pattern, fuel droplet size, and combustion efficiency. Diesel Pro Power provides new, precision-machined tips for:

• N55 – N60 injectors

• N65 injectors

• N70 – N75 injectors

• N80 – N90 injectors

Using the correct injector tip ensures proper atomization, prevents fuel dribbling, and improves overall engine efficiency. New tips are precision-ground to exacting tolerances and undergo multiple flow tests before packaging.

Injector Plungers

The plunger inside each injector acts as a miniature fuel pump, pressurizing diesel before injection. New plungers for N55, N60, N65, and N70 injectors are available, all manufactured to OEM clearances. Worn plungers can cause fuel leaks, poor performance, and reduced fuel economy.

Injector Valve and Spring Assemblies

Injector valves regulate fuel pressure and prevent backflow, while springs maintain consistent seating force. Diesel Pro Power’s valve and spring sets are designed for 53, 71, and 92 Series engines, ensuring reliable performance under all load conditions.

Injector Valve Spring Seat and Injector Spring

The spring seat maintains proper alignment of the valve spring. Replacing worn seats helps sustain consistent fuel pressure, contributing to smoother operation and easier starting.

Governor and Fuel Control Components

The governor on the 3-71 controls fuel delivery based on engine speed and load, ensuring stable RPM and preventing overspeed conditions.

Governor Springs and Adjustment Bolts

Diesel Pro Power carries multiple governor springs and adjustment bolts in various lengths and configurations. Properly tensioned governor springs ensure smooth throttle response and accurate speed control. Adjustment bolts, such as the 2.5-inch and 7-inch versions, provide fine-tuning capabilities for mechanical governors.

Governor Bearings

Bearings in the mechanical governor reduce friction and wear within the control mechanism. Available bearings include upper, lower, and riser bearings for the operating shaft and weights. Replacing these bearings during overhaul helps maintain consistent control response and prevents uneven idling.

Governor Gaskets and Covers

The governor gasket ensures a tight seal between the housing and cover, preventing oil leaks. Available for 2-71, 3-71, 4-71, and 6-71 engines.
For hydraulic governor configurations, Diesel Pro Power also offers gaskets for the governor cover, made from oil-resistant materials for long service life.

Additional Injector-Related Components

Injector Control Tube Brackets and Springs

The control tube transfers mechanical motion from the governor to each injector rack. Diesel Pro Power supplies both the control tube brackets and springs that maintain proper alignment and tension. Replacing these components ensures accurate injector control and smooth acceleration.

Fuel Gauge and Sender Assemblies

Fuel gauges and matching senders are available for Detroit Diesel, Caterpillar, and Cummins engines. These units feature adjustable sender arms and backlit gauges for 12V systems, providing accurate fuel-level readings in marine and industrial applications.

Maintenance Best Practices for Detroit Diesel 3-71 Injectors

To maximize injector life and maintain performance:

1. Use clean diesel fuel – Contaminants can score injector plungers and nozzles.

2. Replace washers and seals during every injector service.

3. Check timing tools for accuracy before use; even minor deviations affect engine balance.

4. Inspect fuel lines for cracks or corrosion. Replace short and long lines as pairs when possible.

5. Lubricate injector racks and control tubes during reassembly to prevent binding.

By following these practices, operators can achieve consistent combustion, reduced smoke, and extended engine life.

Why Choose Diesel Pro Power for Detroit Diesel 3-71 Injector Parts

• Comprehensive Inventory: Every injector, plunger, valve, spring, and timing tool for Detroit Diesel 3-71 engines is available in one place.

• Fast Worldwide Shipping: Orders are shipped same-day with real-time tracking updates.

• Detroit Diesel-Trained Support Team: Our experts can help identify injector types (N55 through N90), timing specifications, and compatibility across 71 Series models.

• Quality You Can Trust: Each rebuilt injector undergoes flow bench calibration to match OEM pressure curves and spray angles.

• Global Reputation: Diesel Pro Power serves over 40,000 satisfied customers across commercial fleets, military vessels, and private marine operations.

Every part listed in this catalog meets or exceeds OEM performance standards, ensuring your Detroit Diesel 3-71 Non-Turbo continues to perform at its best—efficiently, reliably, and powerfully.