Stripped a Head Bolt Hole in my old 406

Discussion in 'High Performance Modifications' started by 1980RS, Apr 7, 2021.

  1. 1980RS

    1980RS Veteran Member

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    Just gave the ARP stud a little test, solid as a rock. Will put the head on after lunch today.
     
  2. carhead22000

    carhead22000 oldblue

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    hopefully after you run engine and retorque it .still be ok...thats when mine failed.goodluck olbuddy.
     
  3. djorgensen3

    djorgensen3 Veteran Member

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    My ARP head studs have the hex key hole in them.
     
  4. 1980RS

    1980RS Veteran Member

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    Well here is what happened with the bolt after lunch. I put the head on and torqued it a bit at #25lbs and it held, but when I got to #45lbs it failed, so plan "B" went into action. I got out the tap set and found a 12X 1.75 pitch metric tap and tapped the hole out and it looked good. I heads over to the local Menards and bought a few bolts as the metric stuff is hardened pretty well. Picked out a couple of stainless bolts and came back to test them, fit perfectly. Now on to the other thinks that came up, I did have to drill the head bolt hole slightly (no biggie) and after that I put the head back on and found that the larger head on the bolt required a 19mm socket to fit, but that will not work on the head as you cannot get the socket on, so out came the bolt. I have a Worksharp sanding disc machine and proceeded to grind down all the flats on the bolt head until a 17mm socket fit right. Put the head back on ran all the bolts down snung inc. the new one and so far so good. 1st pass at #25lbs good on all bolts, 2nd pass at #45lbs good on all bolts, 3rd and final pass all went good and I stopped at bolt 14 and here we go. Made the pull and "click" it worked at #65lbs. on all bolts. Now I have to clean up all the tools and junk just to get one stinkin' bolt to work. Hope the other head is a lot less work.
     
  5. carhead22000

    carhead22000 oldblue

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    glad it worked out for you.
     
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  6. Twisted_Metal

    Twisted_Metal Administrator Staff Member Lifetime Gold Member

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    It’s about time that 12x1.75 tap was put to use!

    Hope that bolt holds! <fingers crossed>
     
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  7. Jodi

    Jodi Veteran Member

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    Nice work there 1980RS...IIRC only the first 3 threads on a bolt that's actually doing the most clamping force the rest are just sort of along for the ride LOL. SBC's design of 5 bolts clamping down per cylinder and all those 5 bolts reaching all the required torque value...you should be golden, again nice work!
     
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  8. G72Zed

    G72Zed Veteran Member

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    Good to hear you got this fixed up 1980RS, I feel your pain when that sh!t happens.
     
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  9. 1980RS

    1980RS Veteran Member

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    Sometimes you just have to use the crap tap to get the job done, Terry. LOL.
     
  10. Cardinal

    Cardinal Veteran Member Lifetime Gold Member

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