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Old 09-01-2013, 04:59 PM   #1
James G.
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Default Broken Head STud - Update

Much labor, small drill bits, dental pick, magnet pickup stick, compressed air, oversize drill + tap, and?
Put the new oversize stud into the block and seated it. Stud was a bit loose near the top where owner had damaged the threads with drill. Mounted the head and began slow torque pattern (from Bratton's catalogue) . 25 ftlb, then 35 ftlb, then 50 ftlb. All went well until the third round on the # 5 stud. At about 45 ftlb or so it gave way.

Now What??? Does anyone make a double oversize head stud?

What we eventually dug out of the broken stud hole included foreign parts like broken "easy-out" tip and broken drill bit tip! This job was in a big mess before we even got started.

Need to get this engine together and running. The owner needs the $. Any ideas on what we need to do now?

I'm in the process of rebuilding the distributor he broke trying to remove the head. He also cracked the head but a club member donated a good used head from a compression upgrade.

We left that head on for now, just trying to decide what to do next! Help!!
Jim G.
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Old 09-01-2013, 05:06 PM   #2
quickchange
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Default Re: Broken Head STud - Update

Drill & fit a helicoil . You need to buy the kit in order to get correct drill etc, Done a number & they work well.
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Old 09-01-2013, 05:16 PM   #3
Kurt in NJ
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Default Re: Broken Head STud - Update

One method is to make your own "insert", pick a size bolt that the oversized hole can be tapped to --it might have to be metric, you don't want to go any larger than you have to, screw in the bolt with locktite, cut it off (sometimes I will pre cut the repair bolt so it will twist off when seated, then draw file it flt to the deck, locate the proper place to drill new hole for stock stud and tap the original size

Another place to look is here-- http://fulltorque.com/ffb.htm
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Old 09-01-2013, 05:36 PM   #4
Bob C
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Default Re: Broken Head STud - Update

I would try to use an insert like in Kurt's link or the one in the McMaster-Carr link.
The 7/16" ones use a 33/64" hole so you can see if you have enough meat left
to use one. http://www.mcmaster.com/#standard-th...nserts/=obn6h2

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Old 09-01-2013, 06:32 PM   #5
Kurt in NJ
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Default Re: Broken Head STud - Update

From what i have read the "oversize stud" is a 1/2 x 13 thread, and that pulled out, the hole must be quite large, this is why I think it might take a custom made piece to fill the hole, --it must be getting close to an edge ---I also have a very nice block that has a hole problem from a botched broken stud drilling and it is at the outside limits of an normal insert repair.
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Old 09-01-2013, 06:59 PM   #6
Mike V. Florida
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Default Re: Broken Head STud - Update

People tend to forget that taps come in different "fits". The most common also give the loosest fit.
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Old 09-01-2013, 08:19 PM   #7
columbiA
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Default Re: Broken Head STud - Update

After you have fitted the largest insert that will not be too close to a cyl or block edge,then temporarily mount the cyl head with about 4 or5 nuts,then useing the head as a guide,use a 29/64" drill bit to center the drill point in the insert. Drill in stages until you are out to the tap size for a 7/16" NC tap.I believe the 29/64" bit will just fit the stud holes in head.
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Old 09-01-2013, 11:53 PM   #8
Ray in La Mesa
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Default Re: Broken Head STud - Update

Look up EZ LOK thread inserts on the internet. They use standard threads and are the simplest, strongest way to go! Much better than Helicoils.
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Old 09-02-2013, 12:24 PM   #9
Pete
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Default Re: Broken Head STud - Update

Kurt in post #3 has about the only alternative left with portable tools.
From what I gather your hole is very close to tap size for 3/8 taper pipe.
In any case tap for this. Get a STEEL, male square drive pipe plug and install
with high temp Loctite. Finish it off flush. Put the head back on with 3 or 4 nuts.
Use it to locate the new stud. Drill and tap for original 7/16-14 thread.
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Old 09-02-2013, 05:24 PM   #10
Russ/40
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Default Re: Broken Head STud - Update

Quote:
Originally Posted by Pete View Post
Kurt in post #3 has about the only alternative left with portable tools.
From what I gather your hole is very close to tap size for 3/8 taper pipe.
In any case tap for this. Get a STEEL, male square drive pipe plug and install
with high temp Loctite. Finish it off flush. Put the head back on with 3 or 4 nuts.
Use it to locate the new stud. Drill and tap for original 7/16-14 thread.
I'll second that great idea.
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