1. Engine Bay Compatibility:
* Size: The Chevy 350 is considerably larger and heavier than the Oldsmobile 260. You'll need to carefully assess whether the 350 will physically fit within the Oldsmobile's engine bay. This often involves modifications, potentially including:
* Firewall modifications: The 350 might hit the firewall. You may need to notch or modify it to provide clearance.
* Inner fender modifications: Similar to the firewall, the inner fenders might require modification or removal to accommodate the larger engine.
* Steering linkage adjustments: The steering linkage might interfere with the engine or accessories. You'll likely need to adjust or replace parts.
* Mounting: The 350 uses a different engine mounting pattern than the 260. You'll need motor mounts specifically designed for a Chevy 350 in an Oldsmobile chassis. These are usually custom-fabricated or purchased from specialty parts suppliers.
2. Transmission:
* Compatibility: The Oldsmobile 260's transmission won't bolt up to the Chevy 350. You'll need a transmission compatible with the 350, such as a TH350, TH400, or 700R4 automatic, or a suitable manual transmission. This will require a new transmission crossmember and potentially driveshaft modifications.
3. Exhaust System:
* Complete Replacement: The exhaust system from the 260 will be incompatible with the 350. A custom exhaust system will need to be fabricated to fit the new engine. This is often done with mandrel-bent tubing for optimal flow.
4. Cooling System:
* Radiator: The stock radiator might be insufficient for the larger 350. A larger capacity radiator, potentially with an electric fan, might be necessary.
* Hoses & Components: All coolant hoses and potentially the water pump will need to be replaced to fit the new engine.
5. Electrical System:
* Wiring Harness: The 260's wiring harness is entirely incompatible. You will likely need a custom wiring harness designed for the 350 or modify a donor harness from a vehicle with a similar engine.
* Alternator: The alternator might need to be changed to match the new setup.
6. Fuel System:
* Fuel Pump and Lines: The 350 will likely require a different fuel pump and fuel lines.
7. Accessories:
* Power Steering: The power steering pump and associated components might need to be changed or adapted.
* Alternator: As mentioned above.
* A/C (if applicable): The air conditioning system might need significant modifications or replacement.
8. Other Considerations:
* Computer Control: Depending on the year of the 350, it might have electronic fuel injection and require a computer and associated sensors. This adds another layer of complexity.
* Driveshaft: The driveshaft length will almost certainly need to be adjusted or replaced to match the new transmission and engine.
* Professional Help: Unless you have significant mechanical experience, this swap is best handled by a professional mechanic specializing in engine swaps. The amount of custom fabrication and problem-solving required is significant.
In short, this isn't a simple bolt-in swap. It's a major project requiring significant mechanical skills, fabrication abilities, specialized tools, and a considerable time investment. The cost can easily range from several hundred dollars (if you have many parts already) to several thousand, depending on the level of professional assistance needed.
