Engatwork, the last time I tried to clean up the threads in aluminum using a tap it ate up all kinds of aluminum filings. I found no trouble in cleaning up the head bolt holes on my 380 as described above. I did not have to use inserts. The bolts torqued up really nicely. However, it was necessary to tap the hole for the insert for my oil pump bolt that had stripped out of the hole. Anyone else with experience on this subject?