* Improved Head Design: Vortec heads feature a revised combustion chamber design, intake and exhaust port shapes, and often roller rocker arms for improved flow and power. The pre-Vortec heads are noticeably different.
* Block Casting Numbers: The casting numbers on the blocks themselves will be different, indicating different manufacturing processes and potentially slightly different dimensions.
* Internal Differences: While the basic architecture remains similar, there may be differences in things like oiling passages or the location of some bolt holes.
While some parts might be interchangeable, you can't just swap heads or other components indiscriminately. Using the wrong parts can lead to serious engine problems. You'll need to check specific part numbers and consult engine manuals to ensure compatibility when working with these different generations of small-block Chevy engines.
