Hi all, after several attempts to seal the leaking inserts in my brothers heads with no success. I purchased an insert kit from Time sert http://www.timesert.com/html/bigsert_sparkplug.html
. This kit was an easy install, I used the aluminum annodized inserts, timesert says they use them to replace the helicoil style inserts we had. With my old inserts out the hole was .660 in., they have an insert thats good for a .720 in. hole. You just install the 14mm insert into the larger insert. Anyway 220 miles so far an no sign of leaking, I have also taken the plugs out several times to see if the inserts would come loose. So far perfect I would highly recommend this fix.