A number 22 head makes the 3 liter 603s. What they should have been from the factory. It was almost a waste putting it on the 3.5 liter 603 engines lower block.

Hard to believe that Mercedes took a good lower block and a poorly designed head. Then went for a poor lower block and an excellent head. You have to really wonder about what they did.

A member some time ago did a rockwell hardness test on the early heads. Some castings where even much softer than others. So quality control was also bad.