BBC bolt threads

I have a 1966 BBC . I have 2 head bolts that the threads are stripped in the block. They had helicoils in them when I took it apart. Now I cannot get them to hold I have tried new helicoils and keyserts neither one will torque anywhere close to 60 lbs. They are the first 2 bolts in front one under the valve cover and the other right below it. Do you have any suggestions ? Can holes be welded shut and start over ? Thank You Richie

well that a good one, i would take it to a machine shop and have them plug it and retap.
welding would end up harden and not able to tap

I agree on going with an automotive machine shop, especially an engine rebuilder. These guys have seen it all. When you say "keyserts", do you mean Keen Serts? Jergens also is a maker of those types of thread repair inserts. They use a thread bigger than normal helicoil repair inserts and hold well. You still might wind up with the shop opting to install an anchored in stud which would in place of using a bolt.

Bob