CJ-2A: Engine, Fuel & Exhaust - The JeepsterMan

CJ-2A: Engine, Fuel & Exhaust

CJ-2A Tech Specs: Unveiling the Heart: Engine, Fuel & Exhaust Specifications

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Welcome back to our journey through the iconic Willys Jeep CJ-2A! In this second installment, we dive deeper into some of the technical intricacies that make this vintage vehicle a marvel of its time, as well as some basic maintenance tips to keep your CJ-2A running smoothly. We will talk about the heart of the machine - the engine, fuel system, exhaust system and the critical components that keep it running.

    Engine Specifications:

    4-134 “Go Devil” L-Head Motor

    • Engine Type: Inline 4-cylinder, L-head (side valve) configuration
    • Displacement: 134 cubic inches (2.2 liters)
    • Bore x Stroke: 3.125" x 4.375" (79.4 mm x 111.1 mm)
    • Compression Ratio: 6.48:1
    • Fuel Delivery: Single-barrel carburetor, commonly the Carter W-O carburetor.
    • Cooling System: Water-cooled with a radiator and water pump & mechanical fan.
    • Ignition System: 6-volt, 4-cylinder, 2-point distributor.
    • Valvetrain: L-Head (flathead) with side-mounted valves
    • Cylinder Arrangement: Inline (all 4 cylinders in a single row)
    • Firing Order: 1-3-4-2
    • Maximum Horsepower: Approximately 60 horsepower at 3,600 RPM
    • Maximum Torque: Approximately 105 lb-ft (142 Nm) at 2,000 RPM
    • Cylinders: 4
    • Idle Adjustment: Typically done manually by adjusting the idle speed screw on the carburetor itself.
    • Throttle Linkage: Mechanical linkage from the accelerator pedal to the carburetor
    • Fuel Metering: Carburetor with manual choke
    • Air/Fuel Mixing: Inlet Manifold (Carburetor Mixing)

    Fuel System Specifications:


    • Carburetor Type: Carter W-O 539S, single barrel carburetor
    • Fuel Delivery: Single barrel
    • Choke: Manual choke
    • Main Jet Location: Inside the carburetor body near the center, often in the main fuel metering circuit
    • Idle Jet Location: Inside the carburetor body in the idle circuit positioned close to the throttle plate or butterfly valve
    • Venturi Arrangement: Single Venturi
    • Material: Cast Iron
    • Identification Tag Location: Typically found on the top or side of the carburetor body

    Fuel Pump:

    • Fuel Pump Type: Mechanical Single Diaphragm Fuel Pump
    • Operation Method: Mechanical, driven by the engine's camshaft
    • Fuel Delivery: Positive Displacement (operated by the engine's camshaft, draws fuel from the tank through an inlet valve, pressurizes it using a diaphragm mechanism, and then delivers the fuel to the carburetor for combustion.)
    • Flow Rate: Typically ranges from about 30 to 60 gallons per hour (GPH) or roughly 113 to 227 liters per hour (LPH).
    • Mounting Location: Typically mounted on the engine block, near the engine's camshaft
    • Check Valve: Equipped with an internal check valve to prevent fuel from flowing back into the tank
    • ID Tag Location: Typically located on the fuel pump body; It may be affixed to the outer surface of the pump housing or located near the inlet and outlet ports of the pump.

    Exhaust System Specifications:

     Exhaust Manifold:

    • Material: Cast iron
    • Design: Integrated with the engine block, facilitating the expulsion of exhaust gases from the cylinders.
    • Mounting: Directly attached to the engine, typically on the side.

    Exhaust Pipe:

    • Material: Steel or similar durable alloy
    • Routing: Extends from the exhaust manifold to the muffler.
    • Function: Transports exhaust gases from the manifold to the next component in the system.


    • Type: Single-chamber design
    • Material: Steel or stainless steel for longevity
    • Purpose: Reduces exhaust noise while directing gases toward the tailpipe.
    • Mounting: Positioned along the exhaust pipe, typically underneath the vehicle.


    • Material: Steel or corrosion-resistant alloy
    • Exit Location: Rear of the vehicle
    • Design: Straight or slightly curved, extending beyond the rear bumper.
    • Function: Guides the final exhaust gases away from the vehicle.

    Exhaust Hangers:

    • Material: Steel or durable alloy
    • Function: Support and secure the exhaust components to the vehicle's chassis.
    • Mounting: Strategically positioned along the exhaust system's length.

    Heat Shield (if applicable):

    • Material: Insulating material, often aluminum
    • Purpose: Shields nearby components from excessive heat generated by the exhaust system.
    • Location: Installed near sensitive areas, such as the fuel tank or suspension components.

    CJ2A Maintenance Tips for the Engine, Fuel & Exhaust Systems:

    Engine Maintenance:

    1. Regular Oil ChangesChange the engine oil and oil filter at regular intervals. This helps to ensure proper lubrication and prolongs the life of the engine.

    1. Check and Change Air Filter: Inspect the air filter regularly and replace it when it becomes dirty. A clean air filter ensures optimal air intake and combustion.

    2. Inspect Spark Plugs: Check and clean or replace spark plugs as needed. Properly functioning spark plugs are essential for efficient combustion.

    3. Timing and Ignition System: Check the ignition timing periodically. Ensure that the ignition system is in good condition for smooth engine operation.

    4. Cooling System Maintenance: Monitor the coolant level and ensure it's at the recommended level. Check for leaks and maintain the cooling system to prevent overheating.

    5. Belt Inspection: Inspect and adjust the drive belts regularly. Loose or damaged belts can affect various engine components.

    6. Valve Clearance: Periodically check and adjust the valve clearance. Correct valve clearance ensures proper engine performance.

    7. Fuel System Inspection: Check fuel lines, connections, and the fuel pump for leaks. Address any issues promptly to avoid fuel system problems.

    Fuel System Maintenance:

    1. Fuel Filter Replacement: Replace the fuel filter at regular intervals. A clean fuel filter prevents contaminants from reaching the carburetor.

    2. Carburetor Adjustment: Periodically check and adjust the carburetor for proper fuel-air mixture. This ensures optimal engine performance and fuel efficiency.

    3. Fuel Pump Inspection: Inspect the fuel pump for any signs of wear, damage, or leaks. Replace the fuel pump if necessary.

    4. Fuel Tank Cleaning: Clean the fuel tank and inspect it for rust or debris. A clean tank reduces the risk of fuel system issues.

    5. Fuel Additives: Consider using fuel additives to keep the fuel system clean and prevent issues related to ethanol in modern fuels.

    6. Tighten and Inspect Connections: Regularly check and tighten fuel line connections to prevent leaks. Inspect the entire fuel system for any signs of wear or damage.

    7. Run High-Quality Fuel: Use high-quality fuel to prevent contamination and deposits in the fuel system.

    CJ-2A Exhaust System Maintenance: 

    1. Visual Checks: Regularly inspect the entire exhaust system for signs of corrosion, rust, or physical damage.
    2. Hanger Inspection: Ensure all hangers are intact and secure, preventing any sagging or misalignment.
    3. Tightening: Periodically check and tighten bolts and clamps to prevent leaks.
    4. Heat Shield Examination: If equipped, verify the integrity of heat shields to safeguard surrounding components.
    5. Muffler Sound: Pay attention to any unusual noises, as they may indicate internal muffler issues.
    6. Rust Prevention: Apply rust-resistant coatings or paints to exposed exhaust components.

    There you have it – a glimpse into the technical specifications that make the Willys Jeep CJ-2A an engineering marvel. Stay tuned for the next part of our series, where we'll go over the cooling system of the CJ2A, and give important tips for maintenance in order to keep your vehicle running smoothly. Remember, when it comes to vintage Jeep parts and expertise, Jeepsterman is your trusted companion on this journey through time.

    #Jeepsterman #CJ2A #VintageJeep #DataPlate #EngineSpecs #FuelSpecifications #WillysOverland

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