Jeep · Willys Go-Devil
Jeep / Willys L134 Go-Devil
The flathead four that powered the wartime Willys MB and became the foundation of early civilian Jeeps.
134.2
Cubic inches
The Go-Devil's power and durability were major reasons Willys won the U.S. military Jeep contract.
Displacement
134.2 ci
Bore
3.125"
Stroke
4.375"
Years
1941–1954 core Jeep era
Key Takeaway
The L134 Go-Devil used a compact 134.2-cubic-inch L-head inline-four with a long 4.375-inch stroke, low 6.48:1 compression, and simple side-valve construction. That layout sacrificed airflow for simplicity, low-speed torque, and reliability in military and early civilian Jeep service.
Technical Specifications
- Compression
- 6.48:1
- Horsepower
- 60 hp @ 4000 rpm
- Torque
- 105 lb-ft @ 2000 rpm
- Architecture
- L-head inline four
- Block
- Cast iron
- Cylinder heads
- Cast iron
- Valvetrain
- Side-valve L-head
- Aspiration
- Naturally aspirated
- Fuel delivery
- Single-barrel carburetor
- Firing order
- 1-3-4-2
The L134 Go-Devil used a compact 134.2-cubic-inch L-head inline-four with a long 4.375-inch stroke, low 6.48:1 compression, and simple side-valve construction. That layout sacrificed airflow for simplicity, low-speed torque, and reliability in military and early civilian Jeep service.
Internal Specifications
Variant-specific values are labeled. Engine families that span multiple years or RPOs can have different heads, cams, induction and rotating parts, so the exact code/year always takes priority.
Notable Applications
Strengths
- Excellent low-speed torque
- Simple rugged design
- Huge historical importance
Weaknesses / Watch-outs
- Flathead breathing
- Three-main-bearing crank
- Low compression
Common Upgrades
- Electronic ignition
- Higher-compression civilian head
- Carburetor and cooling restoration
Racing History & Legacy
The L134 became inseparable from the World War II Jeep story and helped establish the mechanical identity of early civilian Jeeps. Its durable, simple design made it one of the most historically important four-cylinder engines in American vehicle history.
References & Image Credit
Engine image: Greg Gjerdingen · CC BY 2.0 · source
Engineering Notes Worth Knowing
3.125 x 4.375-inch bore and stroke; 134.2 cu in / 2.2 L.
Side-valve L-head architecture with cast-iron block and head.
Factory output listed at 60 hp at 4,000 rpm and 105 lb-ft at 2,000 rpm.
Applications included Willys MB, Ford GPW, CJ-2A, CJ-3A, and M38.
History · context · related reading
The Story Behind Jeep / Willys L134 Go-Devil
The Go-Devil was the engine that powered the Jeep into history. Its modest horsepower was less important than the way it delivered usable torque, tolerated hard service, and fit the compact military vehicle package that became the template for generations of Jeeps.
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