stripped a head stud

midgetchaser

Registered User
well i was putting my heads back on my car and i guess i stripped a head stud because it wont hold torque. i did the three step procedure that is used wiht ARP head stud nut 30-50-75. but i was putting on the last nut and i am about to torque to 75 and i get to about 60 lbs and all of the sudden i watch my needle on my torque wrench fall to 20. i was so pissed and left the stud in there over night, well the nut sealed to the stud and the next day i turned it to tighten it and it wouldnt tighten anymore so im thinking i stripped the stud in the block. could i just retap the block and retap the stud and should it work?
 
The only way to know is to back out the stud and check. If you're using ARPs then odds are you stripped out the block.. the stud itself should be fine. While very unlikely, it's been known to happen. Also, I wouldn't go and replace just that one.. I would start the tightening sequence over again to make sure it's all even.

To answer your question, I don't think it should be a problem to retap the block. Perhaps someone who's been through this could provide a little more insight, though.
 
Last edited:
Heli-Coil

Retapping the block will do no good.
If the thread is stripped out, the material usually there to form the threads has sheared from the block.
I would see if a Heli-Coil insert will work.
If you get a thread repair set it will include a special tap that will thread the block for the insert.
Contact your local engine builder and they could probably give you some info.
Other wise you can order one from a local fastener distributor.
LMK if you have any trouble locating one.
Bill
 
Back that stud out and go get a bottoming tap for that hole. Chances are you have some grit down in the hole and it did not go to the bottom. When you get your nut fully tightend you should only have 1 thread showing over the top of the nut. Hope thats all it is. Mark
 
alright well i tapped it and it was all good untill i discovered the bolt being loose in the hole. it was in all of the way but still moved side to side. so i guess that means an insert is needed. What size? 7/16?
 
blue 94sc gave the best advice in post #3. A heli-coil kit will fix the block threads. Basically a heli-coil is a coil that is threaded inside and outside. The block is drilled and tapped to fit the outside threads of the coil and the inside threads of the coil now fit the stud. John
 
AnnivSpeCpe said:
blue 94sc gave the best advice in post #3. A heli-coil kit will fix the block threads. Basically a heli-coil is a coil that is threaded inside and outside. The block is drilled and tapped to fit the outside threads of the coil and the inside threads of the coil now fit the stud. John

off to Grainger then 7/16 it is. the heli coil ones are the ones that never come out right? oh yea aluminum inserts or steel or does it matter.
 
Best bet would be to bring a stud with you so they can tell what pitch the threads are as well as the size. Sorry to hear it did not work out. Did you figure out what happend. I had a few studs that would not bottom out because of junk in there. I just kept cleaning it out with carb cleaner and a little wire brush till I got the stud to seat. The instructions tell you to use a bottoming tap of good quality but sometimes it takes away some of the material. Hope you get it figured out. Mark
 
scbird1 said:
Best bet would be to bring a stud with you so they can tell what pitch the threads are as well as the size. Sorry to hear it did not work out. Did you figure out what happend. I had a few studs that would not bottom out because of junk in there. I just kept cleaning it out with carb cleaner and a little wire brush till I got the stud to seat. The instructions tell you to use a bottoming tap of good quality but sometimes it takes away some of the material. Hope you get it figured out. Mark

yea i had the bottoming out tap, air compressor and this little pick thing to get everything out. i put the stud in and i could move it back and forth a little so i guess when i tapped it the first time i might have gone in a little sideways. well i found out the stud threads are 7/16-20 they match up perfectly but ill bring it just in case.
 
sail7seas said:
I guess there is not enough clearance to re-tap up .0625" in bolt size.

i wonder if that would fit in the holes that are in the head. i think if i went a 32nd bigger with the bolt it would fit. theres not much room for it to move.
 
Where To: Bottoming Tap

scbird1 said:
......go get a bottoming tap for that hole.
Where can I get a set of bottoming taps? I've been looking for them for years!!!! I'd buy both SAE & Metric, if I could ever find them.

68COUGAR
 
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