1. Engine Bay Clearance:
* Firewall: The biggest hurdle is the firewall. A 454 is considerably wider and taller than the Nova's original small-block or even a big-block intended for the car (if it originally had one). You'll almost certainly need to modify or even replace sections of the firewall to clear the engine's intake manifold, distributor, and valve covers. This often involves cutting, hammering, and welding.
* Inner Fenders: The inner fenders will need significant modification or replacement to accommodate the engine's size. You'll likely have to trim and reshape them to prevent interference.
* Headers/Exhaust: Finding headers that fit a 454 in a '71 Nova is a challenge. Custom-made headers are likely necessary, and the exhaust system will also need to be custom-fabricated to route around frame members and other components.
2. Mounting the Engine:
* Motor Mounts: You'll need engine mounts designed for a big-block in a Nova, likely aftermarket units. These mounts will need to be properly positioned to ensure the engine sits correctly and clears everything.
* Transmission: The transmission choice (TH400 automatic is common) will impact the mounting process. You'll need a compatible transmission crossmember, possibly a custom-fabricated one.
3. Cooling System:
* Radiator: A standard radiator won't suffice. A larger-capacity radiator, possibly with an electric fan, will be necessary to effectively cool the big-block.
* Hoses and Lines: You'll need to adapt or replace the cooling system hoses and lines to fit the new engine and radiator.
4. Drivetrain:
* Drive Shaft: The driveshaft will need to be shortened or lengthened to accommodate the new engine and transmission combination.
* Rear End: The stock rear end may not handle the torque of the 454. Consider upgrading to a stronger unit with appropriate gearing.
5. Other Considerations:
* Wiring Harness: You'll likely need to modify or replace the wiring harness to accommodate the 454's electrical system.
* Brakes: Upgrading the braking system is highly recommended to handle the increased power and weight.
* Suspension: The suspension may need reinforcement to handle the added weight and power.
* Fuel System: The fuel system will likely need upgrades to support the 454's fuel requirements.
In short: This isn't a project for a novice mechanic. It requires significant expertise in automotive mechanics, welding, and fabrication. You'll need access to specialized tools and equipment. Consider consulting experienced engine swap professionals or seeking guidance from online forums dedicated to classic car modifications. Plenty of detailed guides and build threads exist online for similar swaps, which can offer valuable insights. Remember to check local regulations regarding emissions and safety inspections as well.
