Cadillac · Early OHV Cadillac V8
Cadillac 331 OHV V8
The compact high-compression OHV V8 that transformed Cadillac engineering in 1949.
331
Cubic inches
Cadillac's 1949 331 used an oversquare bore/stroke layout, five main bearings and modern overhead valves, cutting major weight and size compared with the old flathead while opening the door to higher compression and power.
Displacement
331 ci
Bore
3.8125"
Stroke
3.625"
Years
1949–1955
Key Takeaway
The 331 replaced Cadillac's flathead with a compact oversquare OHV V8 using a 3.8125-inch bore, 3.625-inch stroke, five main bearings, and hydraulic lifters. The architecture was lighter and better suited to rising compression ratios and higher engine speeds.
Technical Specifications
- Compression
- 7.5:1 in documented 1950 specification
- Horsepower
- 160 hp at introduction; later versions increased substantially
- Torque
- 312 lb-ft in documented 1950 specification
- Architecture
- 90-degree OHV V8
- Block
- Cast iron
- Cylinder heads
- Cast iron
- Valvetrain
- Pushrod OHV with hydraulic lifters
- Aspiration
- Naturally aspirated
- Fuel delivery
- Carbureted
- Main bearings
- 5
The 331 replaced Cadillac's flathead with a compact oversquare OHV V8 using a 3.8125-inch bore, 3.625-inch stroke, five main bearings, and hydraulic lifters. The architecture was lighter and better suited to rising compression ratios and higher engine speeds.
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
- Compact for its era
- Oversquare bore/stroke geometry
- Five-main-bearing bottom end
- Huge historical importance
Weaknesses / Watch-outs
- Early intake and accessory systems are period-specific
- Original performance parts are increasingly collectible
Common Upgrades
- Multiple-carb period induction
- Modern ignition hidden in stock distributor
- Improved cooling and sealing
Racing History & Legacy
The 331 established the architecture that evolved through Cadillac's 365 and first-generation 390.
References & Image Credit
Engine image: Mr.choppers — CC BY-SA 3.0 — via Wikimedia Commons · CC BY-SA 3.0 · source
Engineering Notes Worth Knowing
331 cu in / 5.4 L with 3.8125 x 3.625-inch bore and stroke.
90-degree OHV V8 with cast-iron block and heads.
Five-main-bearing bottom end with hydraulic lifters.
Introduced at 160 hp; documented 1950 torque was 312 lb-ft.
History · context · related reading
The Story Behind Cadillac 331 OHV V8
Cadillac's 1949 331 was one of the engines that changed postwar American performance. It was smaller and lighter than the flathead it replaced and showed how powerful the new generation of overhead-valve V8s could become.
TorqueList Garage Reference Series
See this engine inside the full Cadillac reference catalog.
The same Engine Library data now powers a more detailed mobile-friendly catalog with technical specs, variants, engineering notes, history and related stories.