Well it has to do with those lovely acorn nuts and "checking" the tightness. What size are the studs Jim? I would go out and check put its raining like cats and dogs plus ive had a few and been eating some boiled peanuts. Is it ok to tap the jug? I hope i dont have a new cofee table piece
The studs are M6X1mm...
If the studs pulled out cleanly, you can re-tap the holes 1/4"-20...no helicoils needed.
I use a bottoming tap so that I get the maximum amount of threads for the depth of the hole. Based on SAE standards you will get a 50% thread. This is a minimum, but for this application it's fine!
I re-tap the engine mount holes 1/4"-20 on new engines...they are also M6X1mm.
There is no need to excessively tighten the intake fasteners...after you have re-tapped the holes 1/4"-20, install the longest bolts that you can without bottoming, even if you have to cut down a slightly longer bolt to get full thread engagement to the bottom of the hole.
Edit: Once finished you can snug the bolts up...you don't have to baby it for fear that the new threads will strip. The new threads will not readily strip. Just snug the bolts up tight and leave well enough alone.
Jim