Drilling Exaust manifold stud hole?

[rbduck]

I have a 1990 240sx with the KA24E engine. I had the motor remanufactured. When the guy bolted the exaust manifold onto the head. He pulled the stud and threads out of three holes.The main trouble spots are the two studs closest to the front of the engine. How deep can it be drilled before I cut into either thecooling system or something else bad??

Thanks

[NISTECH]

dont try to go any deeper enlarge the holes to 10mm and use 10mmx1.25 thread studs as replacements. the holes on the manifold are close to 10mm and you get away from risking head damage. you can pick up a tap that size and pitch just about anywhere