Alternator bolt threads stripped in the head

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rklein383

rklein383

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Thought I would work on my son's 67 notchback today and put the alternator on since I had an hour or so to play with it. Realized quickly the threads in cylinder head are stripped. Even worse, there appears to be the remains of a bolt in the hole. I rig up a sleeve to fit around the drill bit that fits inside the hole to keep it centered and start drilling. That's when I find out that what I am trying to drill is hard as hell. I am wondering if it is a broken off easy out.

Crap! I guess I will go get a brand new cobalt drill bit. This could take a while. So much for an easy job....
 
You need a good quality bit

If things really really come to worst, you can always switch the heads side to side
 
I know I can switch the heads side to side... but I really don't want to.
 
If you're going at it with large drill bit ( more than 3/16 ), its center web is too large to cut a good bolt. Use a center drill. I want to say #4 but my memory fails me.
If all else fails, there is a way to use the other hole. Both are 3/8-16 NC .
 
I remember my dad broke the same bolt off on an la engine.
He made a bracket out of 1/4" stock and bolted it to the other bolt hole beside it.
Drilled another hole that ligned up with the broken bolt.
Used washers and spaced everything, did not use the original short alternator spacer.
 
Low cost, easy way, is as already mentioned, swap heads side to side; next you could take a cutting torch, lay the flame directly on the bolt/easy out, and blow the metal out of the hole, it won't stick to the cast iron, nor will the torch won't cut the cast. I personally have not tried this but I have heard of it being done. Next option is to remove the head and take it to a machine shop that has EDM capability, this one will cost, not a huge amount, maybe $30.00-$50.00.

Good luck.
 
I will probably drill out the hole oversize and put in a threaded insert to fix it since the first 3/8 inch of the hole is way over sized already . However, making a bracket and using the other hole with a bracket did cross my mind.
 
I just did an alternator bolt on an Eddy alum. head. This is the best product I could find to replace the threads,works much better than a helicoil & won't back out like a helicoil will. http://www.timesert.com/
 
Helicoil or use what SBeeMan has linked to. It looks good.
 
ok guys this is my first post..i have a 72 dart 4 door with a slant . i just put the slant in it a few days ago and here is my question . my alternator is melting a field wire when i crank it over ...my first thot is a alternator but could it be a ground . how many should i have on the motor i have one from the battery to the p\s bracket . sorry for jacking your post i couldnt figure out how to make one .
 
One ground strap from the right head to the firewall (normally braided stainless steel with crimped on ring connectors on the ends), and the begative cable from the left head or intake bolt directly to the battery. Don't ground to a bracket that bolts to it. Clean the paint off and bolt directly to the head.
 
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