308 head bolt question

hoggyrubber
hoggyrubber Expert Adviser
edited November -1 in HUDSON
any reason why regular grade 8, 2 3/4" 7/16 bolts won't work for head bolts? they are only .130" shorter and have a 5/8 head instead of 3/4, but the grade 8 washers are the same diameter so they should spread the load out the same. 14 of mine were in good shape but 7 had a smaller diameter shoulder toward the head and had quite a bit of pitting so i thought about just replacing those 7.

Comments

  • [Deleted User]
    [Deleted User]
    I've used both sizes successfully, but I never mixed them on a head (the injunear in me). I may be mistaken, but i thought I saw that Dale Cooper was selling the 3/4 head units by the piece or by the set.

    J Cronk
  • PAULARGETYPE
    PAULARGETYPE Senior Contributor
    I DON'T KNOW ABOUT DALE HAVING THEM BUT I SELL 21 GRADE 8,7/16 3" BOLTS THAT HAVE 11/16 HEADS WITH WASHERS FOR $25 + $5 FOR SHIPPING I WOULD NEVER USE A OLD HEAD BOLT THEY WERE GRADE 5 AT BEST IN THE 50'S AND ARE A PAIN IN THE BUT WHEN YOU SNAP ONE OFF I ALSO HAVE 1/2 BY 3" BOLTS FOR THE 7X AND 55,56 308S SAME PRICE
    HUDSONLY
    PAULARGETYPE
  • Geoff
    Geoff Senior Contributor
    My Hornet has only the small headed bolts, with soft washers, so I figure I am inevitably going to have to replace these. I would like to buy a set of these bolts please Paul, can you contact me to arrange. HETgeoffclark@xtra.co.nz Thanks,
    Geoff
  • MikeWA
    MikeWA Senior Contributor
    edited May 2011
    I'm not an expert, but was always told by rebuilder types never to re-use a head bolt, because the torques involved will properly cause the bolt to stretch a little, and the bolt would be compromised if you try to stretch it a second time. At 25 bucks a set, it sure wouldn't pay to take a chance.

    And Paul needs the money, to fix that faulty cap-lock key on his 'puter! :lol:
  • Browniepetersen
    Browniepetersen Senior Contributor
    Not wanting to get technical but here is my take on it. When I did my Salt Flats racer I redrilled the head and went up a size so that I could retap and get good threads in the head. Then taking grade 8 bolts and running them down to the torque following the manufactures recommendations what you actually get is about 80 percent of the pitch/diameter of the threads of the bolt and the hole engaging to get maximum strength. To do anything less than this you are asking for premature failure of the bolt or the threaded hole. Just my .25 cents worth....
  • hoggyrubber
    hoggyrubber Expert Adviser
    thank you all for replys. and mike if paul fixed his caps key he wouldn't be paul LARGE TYPE! :P the torque for these are 60 or 65 ftlbs is pretty low compaired to the inline chevy 292's of 95 ftlbs and most of the bolts are in pretty good shape. i think the 14 ones are rplacements anyway, the have the 6 hash marks for grade 8 and the 7 don't, so i will replace them at least. thanks for all your info everyone and if i decide to change them all out i will send you a email paul.
  • hoggyrubber
    hoggyrubber Expert Adviser
    i made sone of the head installer bolts like it said to use in the shop manual. i cut the heads off and cut a slot in the end for using a screwdriver to keep gasket and head aligned. all i have to say is those old bolts were still pretty tough. i wouldn't worry about them pulling 65 ftlbs! BUT that being said i have never broke off a head bolt, so that would make a guy more cautious. i have conection rod bolts fail as i was torquing them- no fun at all! so i understand and totally respect the cautious route. if any of them start to feel "spongy" i will back it out, if i get the chance. :pinch:
  • DavidC
    DavidC Senior Contributor
    Paul, I will need your contact info for 1/2 by 3 bolt set- can post here or send PM.

    Dave Carpenter
This discussion has been closed.

Categories

In this Discussion