I took some measurements on the exhaust manifold bolts and bolt holes.

The depth of the bolt holes on the head is 22.5 mm
The length of the stud threads is 9.5 mm

So it seems the exhaust studs that thread into the head could have a much longer thread engagement. Why would MB make the threads as short as they did I wonder?

Now the next question is, can I source longer threads that would engage more of the head and be less apt to pull out, strip, or back out

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1982 300SD
1992 190e 2.3 8v
2002 P38 Range Rover