Replacing the original cylinder head screws with high-strength Pro-Series 18.8 studs.
This is necessary when making significant performance increases, as the original cylinder head screws elongate during operation, and the cylinder head can lift off. The Pro-Series 18.8 stud bolts with a tensile strength of 1850 N / mm² provide a solution; these stud bolts do not have to be replaced after dismantling but can be reused.

The Pro-Series 18.8 sets are high-strength stud bolts manufactured in Germany. Special steel is used, which, after tempering, has a tensile strength of 1850 + N / mm².

All threads are formed and not cut as usual. The so-called rolling of threads can increase the strength of the tooth flanks by around 30%. All Pro-Series products are supplied with a nickel coating. Pro-Series stud bolts have a hexagon socket drive on the head side for screwing in the stud bolts.

Due to a cone on the engine block side of the bolt, these are not supported on the thread flanks when the nuts are tightened but in the bore of the thread in the engine block. This support protects the cables when racing engines are frequently rebuilt.

Pro-Series advantage over other manufacturers is the nuts and washers included in the set; these also have a tensile strength of 1850 N / mm².