Chevrolet 350 Small Block V8 Engine Swap Guide For The Nissan 240sx

So, you're thinking about shoehorning a classic Chevy 350 small block V8 into your Nissan 240SX? It's a popular swap, and for good reason. You get a massive power upgrade over the original inline-four, and the 350 is incredibly versatile and readily available. However, be warned: this isn't a weekend project. It's a significant undertaking that requires careful planning, specialized tools, and a healthy dose of patience. This guide will walk you through the key considerations and steps involved, assuming you have intermediate mechanical skills and a solid understanding of automotive systems. We’ll cover everything from engine selection to wiring and cooling, arming you with the knowledge you need to tackle this ambitious swap.

Phase 1: Planning and Parts Acquisition

This phase is absolutely critical. Proper planning will save you time, money, and a whole lot of frustration. Don't skip this!

Engine Selection

The 350 small block is incredibly common, but not all 350s are created equal. Factors to consider include:

Horsepower and Torque Goals: How much power do you really need? A bone-stock 350 can provide a substantial upgrade, while a modified engine can deliver truly impressive numbers. Consider the intended use of your 240SX. Are you building a drift car, a street machine, or something in between?
Engine Type: Are you looking for a crate engine, a rebuilt engine, or a salvage yard pull? Crate engines offer guaranteed performance and reliability, but come at a higher cost. Rebuilt engines can be a good compromise, but do your research on the rebuilder. Salvage yard engines are the cheapest option, but require thorough inspection and likely a rebuild.
Engine Management: Will you be using a carburetor or electronic fuel injection (EFI)? EFI offers better fuel economy, emissions control, and drivability, but requires more complex wiring and tuning. Carbureted setups are simpler but can be less refined.
Budget: Be realistic about your budget. The engine itself is just one piece of the puzzle. You'll also need to factor in the cost of the swap kit, transmission, driveshaft, cooling system, wiring harness, and other miscellaneous parts. It adds up quickly!

Swap Kit Considerations

A swap kit provides the necessary components to physically mount the 350 into the 240SX chassis. A good kit will include:

Motor Mounts: These are crucial for properly positioning the engine in the engine bay.
Transmission Mount: Necessary for securing the transmission to the chassis.
Headers: Designed to fit within the tight confines of the 240SX engine bay and clear the steering shaft and other components.
Oil Pan: A modified oil pan is often required for clearance. Be sure to check for steering rack and subframe clearance.

Research different swap kit manufacturers and read reviews. Not all kits are created equal, and some may require additional modifications. Pay close attention to what the kit *doesn't* include and factor those costs into your budget. Some kits require you to source certain parts yourself, like a specific type of steering shaft or exhaust manifold.

Transmission Selection

The 240SX's original transmission will not bolt up to a Chevy 350. You'll need to choose a suitable transmission, such as:

TH350/TH400: These are robust and relatively inexpensive automatic transmissions. The TH400 is stronger, but also larger and heavier.
700R4/4L60E: These are overdrive automatic transmissions, offering improved fuel economy on the highway. However, they can be more complex and require electronic control.
T5/T56: These are manual transmissions that offer a more engaging driving experience. The T5 is more common and affordable, while the T56 is stronger and can handle more power.

Regardless of your choice, ensure the transmission is in good working order. Rebuilding a used transmission is often a smart investment. You'll also need a compatible bellhousing, flywheel (for manual transmissions), and torque converter (for automatic transmissions).

Other Essential Components

Don't overlook these often-forgotten but essential components:

Driveshaft: The stock 240SX driveshaft will not work. You'll need a custom driveshaft that is the correct length and has the appropriate yokes to mate with the transmission and rear end.
Cooling System: The 350 generates a significant amount of heat. You'll need a high-capacity radiator, electric fans, and suitable hoses.
Fuel System: The stock 240SX fuel pump and lines may not be adequate for a V8. Consider upgrading to a higher-capacity fuel pump and larger fuel lines.
Exhaust System: You'll need a custom exhaust system that connects to the headers and runs to the back of the car.
Wiring Harness: You'll need a wiring harness that connects the engine's sensors and actuators to the car's electrical system. This is a complex task, and a pre-made swap harness is highly recommended.
Gauges: Ensure your gauges are compatible with the V8 engine. You may need to replace or recalibrate your existing gauges.
Battery Relocation: Moving the battery to the trunk can free up space in the engine bay and improve weight distribution.

Phase 2: Preparation and Disassembly

Before you even touch a wrench, prepare your workspace and the 240SX for the swap.

Workspace Preparation

Ensure you have a clean, well-lit workspace with adequate ventilation. Gather all the necessary tools, including:

Metric and standard socket sets
Wrenches
Torque wrench
Engine hoist
Engine stand
Jack and jack stands
Multimeter
Wiring tools (crimpers, strippers, soldering iron)

Having the right tools will make the job much easier and safer.

240SX Disassembly

Remove the following from the 240SX:

Original engine and transmission
Engine wiring harness
Radiator and cooling system components
Fuel system components (as necessary)
Exhaust system

Label all wires and hoses carefully to make reassembly easier. Take pictures throughout the disassembly process. This can be invaluable when you're trying to remember where something goes later on. Consider using zip-lock bags to store hardware from each assembly and label them accordingly.

Engine Preparation

If you're using a salvage yard engine, perform a thorough inspection and rebuild as necessary. This may include:

Checking cylinder compression
Inspecting bearings and crankshaft
Replacing gaskets and seals
Cleaning and painting the engine

Even with a crate engine, it's a good idea to inspect it and install any necessary accessories, such as the intake manifold, carburetor or fuel injection system, and distributor.

Phase 3: Installation and Integration

This is where the real fun (and the real challenges) begin!

Engine and Transmission Installation

Using the engine hoist, carefully lower the 350 into the 240SX engine bay. Align the engine with the motor mounts and secure it in place. Install the transmission and transmission mount. Connect the driveshaft.

Double-check clearances around the engine and transmission. Pay close attention to the steering shaft, exhaust manifolds, and oil pan. You may need to make minor adjustments or modifications to ensure everything fits properly.

Cooling System Installation

Install the radiator, electric fans, and hoses. Ensure there is adequate airflow to the radiator. Consider using a shroud to maximize fan efficiency. Fill the cooling system with coolant and check for leaks.

Fuel System Installation

Install the fuel pump, fuel lines, and fuel filter. Ensure all connections are secure and leak-free. If using EFI, connect the fuel injectors and fuel pressure regulator.

Exhaust System Installation

Install the headers and exhaust system. Ensure there are no exhaust leaks. A poorly sealed exhaust can lead to poor performance, and dangerous fumes entering the cabin.

Wiring and Electrical

This is often the most challenging part of the swap. Using the wiring harness, connect the engine's sensors and actuators to the car's electrical system. Pay close attention to the wiring diagrams and ensure all connections are correct.

Verify that all gauges are working properly. You may need to adjust or recalibrate the gauges to match the V8 engine's parameters.

Initial Startup and Tuning

Before starting the engine, double-check all connections and fluid levels. Prime the oil system by cranking the engine without starting it. Then, start the engine and let it idle. Listen for any unusual noises.

If using EFI, you'll need to tune the engine to optimize performance and fuel economy. This may involve adjusting the fuel maps, ignition timing, and other parameters. A professional tuner can be invaluable in this process.

Phase 4: Troubleshooting and Refinement

Even with careful planning and execution, you're likely to encounter some issues. Be prepared to troubleshoot and refine your setup.

Common Problems

Overheating: Ensure the cooling system is adequate and that there are no air pockets in the system.
Fuel delivery problems: Check the fuel pump, fuel filter, and fuel lines.
Electrical issues: Double-check all wiring connections and grounds.
Clearance issues: Make sure nothing is rubbing or interfering with other components.
Drivetrain vibrations: Ensure the driveshaft is properly balanced.

Refinement

Once you've addressed any major issues, focus on refining your setup. This may include:

Adjusting the suspension to improve handling
Upgrading the brakes to handle the increased power
Adding sound deadening to reduce noise
Fine-tuning the engine for optimal performance

The Chevy 350 swap is a rewarding but challenging project. With careful planning, the right tools, and a willingness to learn, you can transform your 240SX into a powerful and unique machine. Remember to take your time, be patient, and don't be afraid to ask for help. Good luck!