Series Land Rovers

Why does Land Rover use studs instead of bolts on it's exhaust manifolds? Quintin Aspin

It has to do with the comparably low tensile strength of cast iron. If you use studs you are sure that the studs completely bottom in the holes, insuring the maximum amount of thread to manifold area. If you use bolts they might come up tight with 1/4 inch or less engaged in the manifold. And it would be quite easy to rip out the threads. I have learned this little tidbit from experience.

From the OVLR Newsletter January 1996