CJ3A: Engine, Fuel & Exhaust - The JeepsterMan

CJ3A: Engine, Fuel & Exhaust

Powering the Journey: Unleashing the Heart of the Willys CJ-3A

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Engine Specifications

Beneath the hood of the Willys CJ-3A beats the heart of the 4-134 "Go Devil" L-Head motor. Let's explore the mechanical marvel that propels this iconic vehicle forward:

  • Engine Type: Inline 4-cylinder, L-head (side valve) configuration
  • Displacement: 134 cubic inches (2.2 L)
  • Bore x Stroke: 3.125 in x 4.375 in (79.4 mm x 111.1 mm)
  • Compression Ratio: 6.48:1
  • Fuel Delivery: Single Barrel Carter W-O Carburetor
  • Cooling System: Water-cooled with a radiator, water pump, and a mechanical fan
  • Ignition System: Distributor-type with Mechanical Centrifugal and Vacuum Advance
  • Valvetrain: L-Head (Side Valve)
  • Cylinder Arrangement: Inline-4 (all 4 cylinders in a single row)
  • Firing Order: 1-3-4-2
  • Maximum Horsepower: Approximately 60 hp (45 kW) at 4,000 RPM
  • Maximum Torque: Approximately 105 lb-ft (142 Nm) at 2,000 RPM
  • Cylinders: 4 Cylinders
  • Idle Adjustment: Manual, Throttle Knob on Dashboard
  • Throttle Linkage: Mechanical Linkage from accelerator pedal to the carburetor
  • Fuel Metering: Carburetor with manual choke
  • Air/Fuel Mixing: Inlet Manifold (Carburetor Mixing)

Fuel System Specifications:


Meet the Carter WO (Willys-Overland) Model 539S, the culinary artist for the engine:

  • Carburetor Type: Carter WO (Willys-Overland) Model 539S
  • 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
  • ID Tag Location: Usually located on the top or side of the carburetor body

Fuel Pump:

The mechanical maestro that keeps the engine fueled for the journey:

  • Fuel Pump Type: Mechanical Single Diaphragm Fuel Pump
  • Operation Method: Mechanical, Camshaft Driven
  • 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: Engine Block near the 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:

The CJ-3A boasts an exhaust system designed for optimal performance and durability:

  • Type: Single exhaust system
  • Material: Mild steel
  • Muffler: Typically features a single chamber
  • Exhaust Manifold: Cast iron construction
  • Tailpipe Exit: Rear, expelling exhaust gases away from the vehicle
  • Mounting: Securely attached to the engine and chassis for stability
  • Heat Shield: May feature a heat shield near the exhaust manifold for safety and protection

Stay tuned for Part 3, where we delve into the CJ-3A's electrical system and data plate specifics! For authentic parts and expert advice, explore the wide selection at JeepsterMan.

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