Last night tightened the head on my m30 and found out one of the bolt holes is stripped. Been looking on line and it appears that the Time-Sert inserts are the way to go. Has anyone used these to repair the head bolt holes in a iron block. If so what length of insert. I know the threads are M12 x 1.75. The blind holes are around 33-34 mm deep but you need about 6-7mm of free space at the bottom of the hole. The standard length sizes are 18, 24 and 30. I am leaning towards 24. Lots of write-ups for aluminum block but have not seen anything on a iron block repair

Anyone?