Bill - just enough to get the tap started a couple of threads, and then it will take care of itself.
In the "for what its worth" category, the really "tricky" ones are the throttle plate screws. When still doing carburetors, we used to have a lot of units sent to us with a twisted throttle plate screw. We actually received a four-barrel once with ALL eight throttle shaft screws twisted.
Heli-Coil makes the inserts in different lengths; when doing the throttle shaft repairs, use the "short" inserts, or better yet, don't twist off the screws.
Jon
