GM 4.8 cyl head exh bolt

P40E

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Got a broken bolt I still cant get out after trying . I've drilled all the way through it , and almost all of the center already. .

Anyone know for sure how big I can drill out the hole to retap for another bolt ? The original bolt is 8m x 1.25
 

daturbosix

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did you drill the entire bolt out, or most the bolt still there?
 

P40E

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Pretty sure this head is exact to an ls 5.3
 

P40E

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Very first hole in front . Bolt is broke off below the exhaust cyl head hole . (Meaning bolt is broke off about a 1/4 inch down in hole)

Drilled through it with a 3/16 bit . Used heat . Tried my easy outs it won't move .

Hole is now drilled out to 7/32 . There is still some of the bolt outer part left inside the hole .

I believe to tap this hole to the original size (8m x 1.25) , you would use a 17/64 bit . So I still have a little bit to go , just to get back to original size of hole .

Easy outs are tapered. So when I go to use them , the tap goes down into the hole , but bites into the top of the cylinder head hole . .. Because the bolt is broken down into the hole
 

DEEZUZ

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omfg you infantile.... come on bro.... this is elementary
 

P40E

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Gtfo . I want to drill bigger but never drilled into these ls heads . They are tiny . Plus I'm finishing up work that isn't mine . I just want to drill and get this junk out of my bay.
 

DEEZUZ

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Ok... can you at least post a picture?

I mean, do you even know how much more of a bolt is left? I do NOT advise an easy out in this situation... they only make things worse....

You might want to start tapping and hope the remainder of the bolt starts to come out, but I cant be sure, post a pic
 

P40E

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I'm not at work right now .

Like I said I've drilled all the way through the bolt . Which is about an inch long .

I'm thinking of drilling the hole to a cunt hair below original size and then use a tap that is for original thread size.

The hole will either work or not . If it doesn't , I want to know how much bigger I can go . Like to a metric 9m or 10m bolt size But we don't have 9m bolts at work.
 

Yaj Yak

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what'd you do to fix it
 

P40E

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The remaining piece of the bolt finally came out .
 

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