1940 356 Super Eight
1940160 hp
Launch version of Packard’s ultimate classic senior straight-eight
TorqueList Original Technical Art
Packard 356 Super Eight
Inline8 · N/A
Packard · 356 Super Eight
Packard 356 Super Eight
Packard's refined nine-main-bearing flagship straight-eight and one of America's most powerful passenger-car eights at introduction.
356
Cubic inches
The 356 replaced Packard's older senior eights with a smoother, lighter and more modern flagship engine, becoming the prestige powerplant of the One-Sixty, One-Eighty and Super/Custom Clippers.
Key variants
All variants1940 356 Super Eight1946–1947 Super/Custom Super 3561950 Custom Eight 356
Displacement
356 ci
Bore
3.5"
Stroke
4.625"
Years
1940–1950 family era
Key Takeaway
The 356 modernized Packard’s senior straight-eight with 356 cubic inches, nine main bearings, and hydraulic lifters in major production forms. Its 3.50-inch bore and 4.625-inch stroke delivered strong torque while preserving the exceptionally smooth character expected of top-line Packards.
Technical Specifications
- Compression
- 6.45:1 in documented 1940 specification
- Horsepower
- 160 hp in 1940; 165 hp in documented 1947 Super Clipper form
- Torque
- 292 lb-ft in documented early specification
- Architecture
- L-head inline eight
- Block
- Cast iron
- Cylinder heads
- Cast iron
- Valvetrain
- Side-valve L-head with hydraulic lifters in major production forms
- Aspiration
- Naturally aspirated
- Fuel delivery
- Two-barrel carburetion
- Firing order
- 1-6-2-5-8-3-7-4
- Main bearings
- 9
The 356 modernized Packard’s senior straight-eight with 356 cubic inches, nine main bearings, and hydraulic lifters in major production forms. Its 3.50-inch bore and 4.625-inch stroke delivered strong torque while preserving the exceptionally smooth character expected of top-line Packards.
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.
Identification & Output
- Engine codes / RPO
- Super Eight / Custom Super motor-number ranges vary by series; identify by stamped motor number, 3.50 x 4.625-inch bore/stroke and nine-main-bearing 356 architecture
- Casting numbers
- No single universal 356 casting is retained across 1940–1950 production; verify block/head casting with motor number, nine-main-bearing layout and year/application.
- Power rating
- Period brake horsepower / SAE gross-era rating
- Horsepower RPM
- 160 hp @ 3600 rpm in documented 1950 specification; 165 hp factory-rated in 1946–1947 Super/Custom Super form
- Torque RPM
- 280 lb-ft @ 2000 rpm in documented 1950 specification; earlier Packard specifications cite approximately 292 lb-ft depending year
Operating Specs
- Production notes
- Introduced for 1940, the 356 used a 3.50-inch bore, 4.625-inch stroke, nine main bearings and hydraulic lifters in major applications. It remained Packard’s top straight-eight through 1950.
Compatibility Notes
- The 356 is physically and internally distinct from the 288/327 family despite shared 3.50-inch bore dimensions on some engines; crank, block length/main-bearing layout and many external parts differ.
- Hydraulic-lifter and year-specific carburetor/ignition service parts should be matched to the exact motor number and application.
Notable Applications
Packard One-SixtyPackard One-EightyPackard Super ClipperPackard Custom Super Clipper
Strengths
- Nine main bearings
- Exceptionally smooth operation
- Strong low-rpm torque
- Major luxury-car engineering reputation
Weaknesses / Watch-outs
- Large physical length
- Heavy rotating assembly
- Flathead architecture limits modern performance potential
Common Upgrades
- Period-correct carburetor restoration
- Overdrive pairing
- Modern ignition hidden in stock components
Racing History & Legacy
The 356 was not designed as a competition engine; it was Packard’s premium smoothness-and-refinement powerplant. Its nine-main-bearing crankshaft and hydraulic-lifter refinement made it one of the most sophisticated American side-valve eights of its era.
The 356 is widely regarded as the peak of Packard's classic senior straight-eight engineering.
References & Image Credit
Hemmings 1940 Packard Super Eight 160 specs
historical reference
1947 Packard Clipper owner's data
owner manual
Packard straight-eight firing-order reference
technical reference
1946–1947 Packard powertrain specifications
historical specification
Packard 1950s general engine specifications
historical specification
Packard Club — year/model/motor-number identification reference
club identification reference
Key Factory / Build Variants
1946–1947 Super/Custom Super 356
1946–1947165 hp gross
Postwar senior Packard specification
1950 Custom Eight 356
1950160 hp @ 3600 rpm / 280 lb-ft @ 2000 rpm
Final-year 356 application
Engineering Notes Worth Knowing
01
3.50 x 4.625-inch bore and stroke; 356 cu in / 5.8 L.
02
Nine-main-bearing L-head straight-eight.
03
Factory output rose from about 160 hp in 1940 to 165 hp in later Super Clipper form.
04
Documented early torque: about 292 lb-ft.
History · context · related reading
The Story Behind Packard 356 Super Eight
The 356 became the prestige engine behind Packard’s One-Sixty, One-Eighty, and later Super and Custom Clippers. It combined traditional side-valve architecture with unusually refined internal engineering.
TorqueList Garage Reference Series
See this engine inside the full Packard 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.