If you would like to see a good write up on alumunim engine blocks and head bolt repair the mos current would be to look at the installation of time serts in the Cadillac Northstar engine. Most of the technicians that work on these engines tell me that if they R&R the head they timesert every head bolt hole in the block. This is the GM recommended repair for stripped out threads in aluminum engine blocks. Here is a link for more information. ++ TIME-SERT Threaded inserts for stripped threads, threaded inserts, thread repair stripped sparkplug's, Ford sparkplug blowouts, threaded inserts threaded, repair stripped threads, stripped threads, inserts threaded inserts, Ford spark plug repair, Here is the GM discussion. http://www.timesert.com/html/approved-GM2.pdf