Chevy 350 vs Oldsmobile 350
What’s the difference between a Chevy 350 and and Oldsmobile 350? Let’s find out.
The Chevy 350 and Oldsmobile 350 are both 350 cubic inch (5.7L) V8 engines produced by General Motors, but they are entirely different designs with distinct engineering, performance, and compatibility characteristics. Even in the same model year, these engines are not interchangeable and have significant differences in block architecture, dimensions, and components.
Engine Architecture and Dimensions
The Chevy 350 is part of Chevrolet’s small-block V8 family, featuring a 4.00-inch bore and a 3.48-inch stroke. It uses a bore center spacing of 4.4 inches and is known for its compact, lightweight design. The Oldsmobile 350, on the other hand, is part of Oldsmobile’s “Rocket” V8 family. It has a slightly larger bore of 4.057 inches and a shorter stroke of 3.385 inches, resulting in a different internal geometry. The Oldsmobile block also uses a bore center spacing of 4.625 inches, which is unique to Oldsmobile and not shared with Chevy or other GM divisions.[1][2]
Block and Component Differences
Oldsmobile 350 blocks are made of iron with a higher nickel content for added strength, but they are not compatible with Chevy small-block parts. The crankshafts, connecting rods, pistons, and cylinder heads are all unique to Oldsmobile and will not interchange with Chevy components. Oldsmobile 350s always came with iron cylinder heads from the factory, while Chevy 350s could be found with either iron or aluminum heads depending on the application and year. The deck height (distance from the crank centerline to the top of the block) is also different, making the engines physically incompatible for swaps without extensive modifications.[2][1]
Performance and Applications
In the same year, the Oldsmobile 350 (especially the high-performance “Rocket” versions) often produced more horsepower than the base Chevy 350 due to its larger bore and higher compression ratios. For example, the Oldsmobile W-31 350 in 1968–1970 produced 325 hp, while the Chevy 350 LT-1 in 1970 produced 370 hp, but these were special high-output versions. The standard Oldsmobile 350 was typically rated around 250–320 hp, while the Chevy 350 ranged from 165 hp (in later emissions-controlled versions) up to 350 hp in performance trims. Both engines powered a wide range of GM vehicles, but the Oldsmobile 350 was used in Cutlass, 442, and other Oldsmobile models, while the Chevy 350 was found in Camaro, Chevelle, Corvette, and countless trucks and vans.[3][1][2]
Compatibility and Swapping
The Chevy 350 and Oldsmobile 350 are not bolt-in swaps for each other. Their engine mounts, bellhousing patterns, oil pans, and accessory drives are all different. Even transmissions (like the TH350) require different adapters or custom mounts. The Oldsmobile 350 is considered a “small block” within Oldsmobile’s lineup, but it is not related to the Chevy small-block family in terms of parts or dimensions.[4][5]
Summary Table
| Feature | Chevy 350 (Small-Block) | Oldsmobile 350 (Rocket V8) |
|---|---|---|
| Bore x Stroke | 4.00" x 3.48" | 4.057" x 3.385" |
| Bore Center Spacing | 4.40" | 4.625" |
| Block Material | Iron (some aluminum heads) | Iron (higher nickel content) |
| Cylinder Heads | Iron or aluminum | Iron only |
| Deck Height | ~9.025" | ~9.5" |
| Typical Horsepower | 165–370 hp (varies by year) | 160–325 hp (varies by year) |
| Interchangeability | Chevy-specific parts | Oldsmobile-specific parts |
| Transmission Mount | Chevy-specific | Oldsmobile-specific |
Both engines are iconic in their own right, but they are fundamentally different in design, performance, and compatibility.
References:
https://www.jalopnik.com/2019811/chevy-350-vs-oldsmobile-350-differences/
https://www.slashgear.com/1532019/oldsmobile-350-chevrolet-350-engine-difference-explained/
https://www.jalopyjournal.com/forum/threads/diff-between-olds-buick-and-chevy-350s.338781/
https://www.facebook.com/groups/138359353403/posts/10162046413628404/
https://forums.aaca.org/topic/101858-olds-350-vs-chevy/
https://autos.yahoo.com/classic-and-collector/articles/chevy-350-vs-oldsmobile-350-012500897.html