* Larger Displacement: The most obvious difference is its 340 cubic inch (5.6L) displacement compared to the smaller 273 and 318 engines. This provides significantly more power potential.
* Higher Compression Ratio: The 340 typically had a higher compression ratio than the 273 and 318, leading to more efficient combustion and more power. This often meant a higher-octane fuel requirement.
* Forged Internal Components: Many 340s (especially those intended for performance applications) utilized forged internal components like connecting rods and crankshafts. These are stronger and can handle higher RPMs and greater stress than the cast components often found in the smaller engines.
* Different Cylinder Heads: The 340 used specific cylinder heads designed for better airflow and increased power. These heads had larger intake and exhaust ports and often different combustion chamber designs compared to the 273 and 318 heads.
* Higher-Performance Camshaft: The 340 typically included a camshaft with more aggressive valve timing profiles, leading to increased power at higher RPMs.
* Optional Equipment: Depending on the year and options, 340 engines could include additional performance features like higher-flow carburetors, upgraded intake manifolds, and dual exhaust systems.
In short, the 340 "wedge" wasn't just a bored-out version of a smaller engine; it was engineered from the ground up with performance as a primary goal. The combination of larger displacement, stronger internals, and performance-oriented components resulted in a significant increase in horsepower and torque compared to the more commonplace 273 and 318 engines.
