Case savers and Machining!!

[biggtbiggt]

I am in the middle of rebuilding a 1975 7R 2.7 and have found failed helicoils. I am going to install case savers to fix this problem. As I have allready had helicoils put in the machinists said I should install the 14x2 case savers rather than the 12x1.5 because there will not be enough threads left to grab. After looking at my case for awhile I am scared that if the 14's pull out that there is no room to go larger. I have found some case savers that are 1/2" on the outside and 10mm inside. Since 1/2" is approx. 13mm that would still give me 1mm still left in my case. I am also considering building some of these case savers myself. If anybody has done this in the past please post your info! As I have found that the recommended case saver for my application would be a 14x2 outside, I am wondering if a 1/2x13 will hold as good as the thread pitch is very close!

thanks...Tracy