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1970 134 Fhead Head Gasket Replacement

Discussion in 'Early CJ5 and CJ6 Tech' started by jeepstar, Nov 14, 2016.

  1. Nov 21, 2016
    PeteL

    PeteL Member 2020 Sponsor 2019 Sponsor

    Hills of NH
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    Thing is, they may actually be expected to stretch, and recover, within certain elastic limits over thousands of heat cycles, and to protect the head gasket by doing so.
    A bolt which undergoes plastic deformation never recovers fully and no longer provides adequate clamping.

    Grade 8 may be more brittle than a designated head bolt with a planned resilience. Bigger numbers are not necessarily appropriate or better.

    Carroll Smith's Nuts, Bolts, Fasteners and Plumbing Handbook (Motorbooks Workshop): Carroll Smith: 9780879384067: Amazon.com: Books
     
    Last edited: Nov 21, 2016
  2. Nov 21, 2016
    jeepstar

    jeepstar Well-Known Member 2020 Sponsor

    Sheboygan
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    Interesting read!
     
  3. Nov 27, 2016
    jeepstar

    jeepstar Well-Known Member 2020 Sponsor

    Sheboygan
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    Put all head bolts in finger tight. Then i put all head bolts in at 30lbs. Then was going for round 3 at 60lbs. All was fine until i got to bolt 9 in the tightening sequnce. i thought i snapped the bolt. it gets snug, then spins. should i get a 1/4" longer bolt? Yes I rethreaded all of the stud holes and the bolts with a tap and die set prior to starting
    20161127_123517.jpg
     
  4. Nov 27, 2016
    Twin2

    Twin2 not him 2020 Sponsor 2019 Sponsor

    Virginia Beach, VA
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    with bolt unscrewed and just sitting in hole . how much bolt is sticking above head
    sounds like it helicoil time . and you got to start all over again :(
     
  5. Nov 27, 2016
    jeepstar

    jeepstar Well-Known Member 2020 Sponsor

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    Just under a half inch. so what happened? it bottomed out and stripped at that depth?
     
    Last edited: Nov 27, 2016
  6. Nov 27, 2016
    PeteL

    PeteL Member 2020 Sponsor 2019 Sponsor

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    "Just under a half inch"

    Not bottomed, unless it snapped off at the tip. Unlikely with Grade 8.

    Just the opposite. Half an inch ain't near enough thread engagement length. Stripped the block threads with the hardened bolt threads.

    Adding another ¼" won't make it. Helicoil. AND get the right bolt length for all the other holes.
     
    Last edited: Nov 27, 2016
  7. Nov 27, 2016
    jeepstar

    jeepstar Well-Known Member 2020 Sponsor

    Sheboygan
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    What is the proper bolt length?
     
  8. Nov 27, 2016
    Howard Eisenhauer

    Howard Eisenhauer Super Moderator Staff Member

    Tantallon, Nova...
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    Exact same thing happened to me- I just helicoiled it & all was fine.

    Proper sizes are-

    7/16-14 x 1 11/16 1

    7/16-14 x 4.25 14

    The 4.25 are hard to find, I bought 4.5's & cut 1/2' off the ends.


    H.
     
  9. Nov 27, 2016
    Focker

    Focker That's what I do, I know things and I fix stuff. Staff Member 2019 Sponsor

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    Wouldn't that end up being 4.0?
     
  10. Nov 27, 2016
    jeepstar

    jeepstar Well-Known Member 2020 Sponsor

    Sheboygan
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    Is there a sleve in the head then? Do i get a smaller bolt for the helicoil insert? i have to drill out the hole larger, then tap it, insert the helicoil, and use the same size bolts?

    Ive never helicoiled anything
     
    Last edited: Nov 27, 2016
  11. Nov 27, 2016
    jeepstar

    jeepstar Well-Known Member 2020 Sponsor

    Sheboygan
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    And i can reuse the gasket, right?
     
  12. Nov 27, 2016
    PeteL

    PeteL Member 2020 Sponsor 2019 Sponsor

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    Head bolts are as Howard describes. Four and one-quarter inch long.

    Part #805730 (14 of 4-¼")
    Part # 801000 (1 of 1-11/16")
     
  13. Nov 27, 2016
    jeepstar

    jeepstar Well-Known Member 2020 Sponsor

    Sheboygan
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    I googled the part numbers. where did you get them from? or is that the fsm bolt part #?
    Can i go to a local hardware store for a helicoil?
     
  14. Nov 27, 2016
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    No. Sorry. :(
     
  15. Nov 27, 2016
    PeteL

    PeteL Member 2020 Sponsor 2019 Sponsor

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    1955 Jeep Parts Book

    A good hardware may have helicoils, otherwise it will be a FLAPS. You'll probably have to buy several in a pack. Get the special tools too.
     
  16. Nov 27, 2016
    Glenn

    Glenn Kinda grumpy old man Staff Member

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    Yes.
     
  17. Nov 27, 2016
    jeepstar

    jeepstar Well-Known Member 2020 Sponsor

    Sheboygan
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    Whats a flaps? im not clever with acronyms
     
  18. Nov 27, 2016
    timgr

    timgr Jeepin' Nerd 2020 Sponsor 2019 Sponsor

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    Friendly local auto parts store.
     
  19. Nov 27, 2016
    jeepstar

    jeepstar Well-Known Member 2020 Sponsor

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    Wife says to buy a new motor and stop messing with this old one. i keep saying honey, eventually it will be a new motor...
     
  20. Nov 27, 2016
    jeepstar

    jeepstar Well-Known Member 2020 Sponsor

    Sheboygan
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    Couldnt guess the "f".

    How do i drill it out? hand drill seems like a bad idea
     

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