Buying guide and details
Rod and head
Rod bolts hold the rod together on every revolution, and when revs climb they are the first thing to let go. Head studs keep the head clamped when combustion pressure goes beyond what the factory engine makes. Both are replaced whenever the engine is opened.
A rod bolt rarely fails from a single pull. It fails from fatigue, after millions of stretch cycles. ARP rolls the thread after heat treatment, not before, and that step gives fatigue resistance at the thread root, where the crack starts.
Materials
8740 is the base steel. L19 and Custom Age 625 are stronger alloys, for high rpm and loads that 8740 can no longer carry. The material is listed on every kit.
How to choose
By the engine code in the title. If your engine is not listed, write to us: ARP has a larger catalogue than the one we keep on the shelf.




































