1. Heads and Engine Compatibility: Ensure the 400 heads are compatible with your 350 engine. Some modification might be necessary, such as valve sizes or port matching, to achieve proper fitment and performance.
2. Compression Ratio: Changing cylinder heads can alter the compression ratio of your engine. Higher compression ratios generally lead to increased power, but they also require higher-octane fuel to prevent knocking and potential damage. Calculating and adjusting for the appropriate compression ratio is crucial.
3. Valves and Port Sizes: The 400 heads might feature larger valves and improved port design compared to the original 350 heads. Larger valves and optimized porting can enhance airflow and volumetric efficiency, resulting in more power potential.
4. Camshaft Compatibility: The camshaft profile designed for the 350 engine might not be optimal for the 400 heads. Consider upgrading to a camshaft that's compatible with the new heads and matches your performance goals.
5. Other Components and Tunings: Swapping heads might require adjustments to other components like intake manifold, exhaust, fuel injector, and ignition timing. Proper tuning (e.g., using a dyno) is crucial to optimize performance and ensure safe engine operation.
In general, if you're looking for a moderate power gain and are prepared for the necessary modifications and tunings, installing 400 heads on a 350 engine might be a worthwhile upgrade. However, the cost might outweigh the benefits if you're aiming for significant power increases or simply looking for a simple and reliable setup.
