Just finished a Hg job on my 3L. While installing the cam the front right/right cam bearing cap bolt stripped out the threads in the head. Bought a heli coil set fixed it problem solved.
So when I was torqueing down the cam I was extra careful the next time to make sure there was the least amount of pressure from the valves pushing on the cams. In sequence with a torque wrench the other cap bolt stripped the head out too.
WTF, fixed it, cleaned it, torqued it, spec'd it, put the valve covers on and went to the next head.
Then the same cap on the next head stripped both bolts. Needless to say I'm pretty dam good at these by now, so got it done. Quick too, not a good situation but a good expierence as far as learninga skill.

So can anyone explain this? Has this happened to anyone else? I'm pretty comfortable with my tap/die set but I've never ran into something like this before.
Oh ya this is the second hg job the engines been through, the last one was a recall in 98.

 

It's happened to me twice. I didn't have a repair kit, so I just used longer bolts and an extra spacer or two.

I have no definitive explanation for it other than it's just stinkin' soft aluminum. I was in the same situation as you with my 3.0....and, as others have been who've also run into this issue....where I was mindful of everything yet the threads still stripped. Buggers!!

On my 22re, I has stripped out some exhaust studs. I was being quite careful, too. Only this time I went and purchased a repair kit and now have two inserts in the head. I like them over the original threads, personally. They accept studs/bolts much more smoothly and feel more secure when torquing.

 

did you chase the treads with the tap and die before you put the bolts in cause oil and junk gets in there and bamm there goes the treads or did you cross thread them

 

No cross threading this time. They went in smooth they just never grabbed a hold of anything. Then when the bolt came out it took the threads with it.
I never tapped em either. I ussually spray each hole with brake or carb clean and blow em out with an airline. I think even if I did tap em it wouldn't have helped. It was just the aluminum that didn't hold up.