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Fix for broken stripped head bolt?


stony

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Block is stripped out? A helicoil should be more than enough to repair it.... if you're superparanoid you can double insert it for twice the required thread engagement. 

 

Remember that the bolts only go so deep, so it's not stripped all the way down, with some careful measuring and a floor mounted drill press (Or mag-base drill) you can take out the threads to the proper depth to allow a double insert to seamlessly mesh with the remaining threads in the bottom of the hole...but it's probably not necessary.

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You could theoretically go with the 12mm diesel head bolts...but I'm not sure of the particulars on that...length, what you have to do to the mating head holes, etc.

 

Cosmoline/Grease it up good, and stick it in a corner. One bolt is easy to dismiss when you can get another block easily...in a few more years people will give you their first born to get a block with only one bolt hole stripped!

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I had one break off into the head/block and had to weld a nut onto what was left to try and back it out. Before it was all said and done I messed up the threads so bad I had to re -drill and use Heli -coils just like mentioned above! It seems you have these problems more frequently when matting a alumminum head to a cast block or vice versa. A good torqable anti sieze will save you some headaches down the road. Thats my only advice.

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BMW has the proper bolts for the 12MM headbolt swap. DAW has the information on it; there was another here who also had the numbers.

 

I am sure a properly selected length of B7 threaded rod 12mmx1.5 would be suitable for the head bolt clamping force required, but I would still be running the numbers to be sure.

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