stripped head bolt threads

*Disclaimer* - you "should" use a milling machine or similar set up to ensure the drill goes in perfectly straight into the hole.

Get a Heli-coil set (or other thread insert) from your local harware store for a 7/16-14 size. Get the whole kit with the drill bit, tap, heli-coils and installation tool. I used a hand drill and checked for straightness on two sides, then drilled into the stripped hole using the supplied drill bit - is should go through like a hot knife through butter if you are lined up right, you are really only shaving the threads out. Now here is the REALLY important part - using the provided tap - tap new thread into the fresh hole you just drilled. MAKE SURE the tap is going in perfectly straight into the hole. You can tweak it a bit within the first few threads cut - but after that, forget it. If you are the slightest bit off - the studs/bolts will not line up right with the head and may require a little "modification" to the sides of the hole in the head to get them to fit... I used a framing square flush to the block and checked two sides 90 degrees apart MANY times during the process. Now that you have nice pretty threads cut into the block, put a little permanent thread locker on the inserts and screw them into place and WHOO-LAAA, a nice new head stud/bolt hole with new clean threads that are stronger than the originals.

Not too bad once you get the hang of it.

Dan

• Helical Thread Insert