1. Choosing the Fuel Injection System:
* Modern EFI: The most common approach is to install a modern electronic fuel injection (EFI) system. This involves sourcing a complete EFI kit specifically designed for your engine (likely a Nissan Z24 or Z24E).
* Older EFI: You could opt for a used fuel injection system from a later-model 720 or a compatible Nissan vehicle. This might be more affordable but may require more modification and have less advanced features.
2. Engine Compatibility:
* Engine Type: The 1985 720 likely has a Z24 or Z24E engine. Check the engine code to confirm.
* Engine Modifications: Ensure your engine is compatible with the chosen fuel injection system. Some modifications, like upgrading the camshaft, may be necessary.
3. Parts and Components:
* Fuel Injection Kit: This includes fuel injectors, fuel rail, fuel pressure regulator, fuel pump, and wiring harness.
* Engine Management System: You'll need an ECU (engine control unit) to manage the fuel injection system.
* Sensors: Oxygen sensor, coolant temperature sensor, throttle position sensor, and more.
* Wiring Harness: A new wiring harness for the fuel injection system will be required.
* Intake Manifold: You might need a new intake manifold designed for fuel injection.
4. Installation Process:
* Remove Carburetor: Remove the carburetor and all associated components.
* Install Fuel Injection System: Mount the fuel rail, fuel injectors, and fuel pressure regulator on the intake manifold.
* Install Fuel Pump and Lines: Install the fuel pump and connect fuel lines to the tank and fuel injectors.
* Install Engine Management System: Mount the ECU and connect the sensors and wiring harness.
* Wiring and Connections: Carefully wire and connect all components, ensuring proper grounding and polarity.
5. Tuning and Calibration:
* ECU Programming: The ECU will need to be programmed and calibrated for your specific engine and fuel injection system. This may require professional assistance or specialized software.
* Initial Start-up and Adjustments: Once installed, you'll need to start the engine and make adjustments to the fuel pressure, air/fuel mixture, and other parameters to ensure optimal performance.
Challenges and Considerations:
* Complexity: This is a major mechanical project requiring a high level of expertise and knowledge.
* Cost: Parts and labor can be expensive, and professional installation might be necessary.
* Emissions: The conversion may affect emissions compliance.
* Vehicle-Specific Issues: There may be specific challenges related to your 1985 720 model and engine.
* Safety: Proper installation and wiring are critical to avoid potential safety risks.
Alternatives:
* Professional Conversion: Consider having the conversion done by a qualified mechanic specializing in fuel injection conversions.
* Carburetor Overhaul: A thorough overhaul of your existing carburetor could offer a less expensive and simpler alternative to fuel injection.
Recommendation:
If you're not a seasoned mechanic with experience in fuel injection systems, it's highly recommended to consult with a professional for this conversion. They can assess your vehicle's compatibility, recommend the best fuel injection system, and handle the installation and tuning professionally.
