Here's why:
* Valve Size and Position: Even if the heads look similar, the valve sizes and positions may differ between the 3.1L and 3.4L engines. This could cause interference issues.
* Combustion Chamber Design: The combustion chambers in the heads may be different sizes and shapes, affecting compression ratio and performance.
* Other Mounting Points: There might be differences in the mounting points for the head, making it incompatible with your 3.4L engine.
Recommendations:
* Consult a Mechanic: The best way to ensure compatibility is to consult a qualified mechanic. They can examine the heads and determine if they are interchangeable.
* Check OEM Parts Catalog: Refer to a parts catalog from the manufacturer (GM in this case) for specific information on head cylinder compatibility.
* Research Online: Search for online forums or communities related to Pontiac Transports. You might find discussions or resources regarding head cylinder swaps.
Remember, attempting to use incompatible parts can lead to serious engine damage. It's always better to be safe and consult with a professional before making any modifications.
