TorqueList Original Technical Art
Cadillac 346 Flathead V8
V8 · N/A
Cadillac · L-Head Cadillac V8
Cadillac 346 Flathead V8
The long-stroke prewar Cadillac V8 that powered the division through World War II and into 1948.
346
Cubic inches
The 346 was Cadillac's mature prewar flathead V8 and powered a broad range of luxury cars as well as wartime military applications before the revolutionary 331 OHV engine replaced it.
Displacement
346 ci
Bore
3.5"
Stroke
4.5"
Years
1936–1948
Key Takeaway
The 346 used a traditional 90-degree L-head V8 layout with a 3.50-inch bore and very long 4.50-inch stroke. Heavy cast-iron construction and side-valve breathing favored quiet low-speed torque and smooth luxury-car operation over high-rpm power.
Technical Specifications
- Horsepower
- Varies by year/application; see documented variants
- Torque
- 283 lb-ft @ 1700 rpm in representative 1941 Cadillac 346 specification
- Architecture
- 90-degree L-head flathead V8
- Block
- Cast iron
- Cylinder heads
- Cast iron
- Valvetrain
- Side-valve L-head with hydraulic lifters in later/common production form
- Aspiration
- Naturally aspirated
- Fuel delivery
- Carbureted
- Main bearings
- 3
The 346 used a traditional 90-degree L-head V8 layout with a 3.50-inch bore and very long 4.50-inch stroke. Heavy cast-iron construction and side-valve breathing favored quiet low-speed torque and smooth luxury-car operation over high-rpm power.
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
- Smooth hydraulic-lifter operation
- Major prewar Cadillac heritage
Weaknesses / Watch-outs
- Flathead airflow limits compression and performance
- Very long 4.50-inch stroke
- Heavy compared with the 1949 OHV replacement
Common Upgrades
- Period-correct carburetor restoration
- Electronic ignition conversion
- Cooling-system restoration
Racing History & Legacy
The 346 closed Cadillac's flathead era and set the stage for the much lighter 331 OHV V8.
References & Image Credit
Engineering Notes Worth Knowing
346 cu in / 5.7 L with 3.50 x 4.50-inch bore and stroke.
90-degree flathead V8 with cast-iron block and heads.
Hydraulic lifters appeared in later/common production form.
Used across prewar and immediate postwar Cadillac models and in wartime military applications.
History · context · related reading
The Story Behind Cadillac 346 Flathead V8
The 346 represents the final mature form of Cadillac's flathead V8 tradition. It powered the brand through the late prewar years, wartime service, and the first postwar cars before the revolutionary 331 arrived.
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