1. Major Differences & Challenges:
* Engine Bay: The 1955 Pontiac's engine bay is significantly smaller and designed for a much smaller engine. The 389 is substantially larger and longer. You'll need to heavily modify or even fabricate new firewall sections, inner fenders, and possibly even the radiator support.
* Mounting: The 389's engine mounts will not align with the 1955 frame. You'll need custom motor mounts fabricated.
* Transmission: The 389 likely came with a different transmission than the 1955. You'll need to adapt the transmission to the 1955's bellhousing, driveshaft, and rear end. This may involve custom driveshafts, potentially a different rear end altogether for proper gearing.
* Exhaust: The exhaust system will need to be completely custom-fabricated.
* Wiring Harness: The wiring harness from the 1964 engine will be incompatible. You'll need to either adapt the existing harness or create a custom harness.
* Cooling System: The cooling system will likely need upgrading to handle the larger engine. This might include a larger radiator, different water pump, and possibly electric fans.
* Steering: The larger engine may interfere with steering components. Modifications might be necessary.
* Fuel System: You'll need to ensure compatibility between the fuel system of the 389 and the 1955's fuel tank and lines.
2. General Steps (High-Level Overview):
1. Research & Planning: This is crucial. Thoroughly research the specifics of both the 1964 389 and the 1955 Pontiac chassis. Gather information on engine dimensions, transmission compatibility, and potential clearance issues. Consider consulting with experienced hot rodders or engine swap specialists.
2. Disassembly: Completely remove the existing engine and transmission from the 1955.
3. Fabrication: This is the most significant part. This will include:
* Firewall Modification: Cutting and shaping the firewall to accommodate the 389.
* Custom Motor Mounts: Fabricating mounts that securely and correctly position the engine.
* Inner Fender Modification: Modifying or replacing the inner fenders to clear the engine and accessories.
* Transmission Adaptation: Adapting the transmission to the 1955's drivetrain. This might involve bellhousing modifications, custom driveshafts, and possibly a rear-end swap.
* Exhaust Fabrication: Constructing a custom exhaust system.
4. Engine Installation: Carefully install the engine and transmission using the custom mounts.
5. Wiring: Install the adapted or custom wiring harness.
6. Cooling System Installation: Install the appropriate radiator, water pump, hoses, and potentially electric fans.
7. Fuel System Installation: Adapt or install the fuel system.
8. Testing & Tuning: After installation, thoroughly test the engine and perform any necessary tuning.
3. Necessary Skills & Tools:
This project requires advanced mechanical skills, welding expertise (likely MIG and TIG), fabrication skills, and a wide range of tools, including:
* Welding equipment
* Cutting tools (plasma cutter, saws, grinders)
* Engine hoist
* Various hand tools
* Fabrication equipment (metal bending brakes, etc.)
4. Professional Help:
Unless you have extensive experience with engine swaps and fabrication, it's highly recommended to seek professional help from a qualified mechanic or hot rod shop specializing in engine swaps. This project is extremely complex and attempting it without the necessary skills and equipment could lead to significant damage or injury. The cost of professional assistance will likely be substantial, but it's a wise investment to ensure a successful outcome.
