Torque Procedure and Bolt Stretch Explained

Our Question of the Week this week is about headstuds and assembly Lube. The specific question was can you use ARP assembly lube with a factory Subaru headbolt, and it turns out that is not an easy question to answer.

Our friend and customer Drew has a broad engineering background, and he has also built a couple of Subaru engines, so he was a perfect person to have a conversation with about what happens when you start to deviate from the standard directions with something like a headstud.

And it turns out that even small changes can make big differences here.

We talk about the Subaru factory headstuds/headbolts, ARP headstuds, ARP assembly Lube, torque to yield bolts, and bolt stretch.

Hopefully this gives you a better picture of what is going on when you are torquing down a bolt, and how much goes into building up the instructions that you get from a manufacturer.

Thanks for watching and Stay Tuned!