removing exahust stud
Make a jig or rig a manifold (junker?) to use as a drill guide. If you have a press, lathe, etc, drill a small grade 2 bolt to use as a bushing, IE saw off a bolt so it fits the top of the manifold, with maybe 1/4" or so of bolt shank to pilot into the manifold hole. Then carefully drill the bolt with maybe a 1/8 bit for a pilot.
Don't forget helicoils or other "thread inserts" to repair a screw-up
Another thing that can be handy is one of those "drill guides." I don't know if anyone still makes 'em. They were a deal that you hooked a drill to, had a second chuck on a shaft on sliding rails. A "shoe" on the bottom allowed you to hold the drill perpendicular to the work
This one is not exactly what I was talking about, but the same idea:
Make a jig or rig a manifold (junker?) to use as a drill guide. If you have a press, lathe, etc, drill a small grade 2 bolt to use as a bushing, IE saw off a bolt so it fits the top of the manifold, with maybe 1/4" or so of bolt shank to pilot into the manifold hole. Then carefully drill the bolt with maybe a 1/8 bit for a pilot.
Don't forget helicoils or other "thread inserts" to repair a screw-up
Another thing that can be handy is one of those "drill guides." I don't know if anyone still makes 'em. They were a deal that you hooked a drill to, had a second chuck on a shaft on sliding rails. A "shoe" on the bottom allowed you to hold the drill perpendicular to the work
This one is not exactly what I was talking about, but the same idea: