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Stag engine cylinder head stud removal

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    #16
    Julian thanks,
    I have started to trawl through other old strings on this forum on the subject of studs and their removal and replacement with bolts. One string that I found interesting was from Marco Polo who said there was an 'upgrade' offer made available for TR7s exported to the US which was a set of bolts to replace the long studs similar to those in the Stag.
    Anyway, I'll get back to some more string trawling on the subject .... I feel a letter coming on for the magazine ....are you there V Mad?

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      #17
      This was my solution.
      Obtained bolts from local supplier.

      2013 - Copy.JPG
      Originally posted by Tony Triumph View Post
      Julian thanks,
      I have started to trawl through other old strings on this forum on the subject of studs and their removal and replacement with bolts. One string that I found interesting was from Marco Polo who said there was an 'upgrade' offer made available for TR7s exported to the US which was a set of bolts to replace the long studs similar to those in the Stag.
      Anyway, I'll get back to some more string trawling on the subject .... I feel a letter coming on for the magazine ....are you there V Mad?
      John

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        #18
        Hi John,
        Where did you buy the bolts and which strength do they show?

        Klaus

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          #19
          2013.JPG

          High Klaus,

          They are grade 8, obtained from a local nuts and bolt wholesaler.

          John.

          Originally posted by Klaus Schlueter View Post
          Hi John,
          Where did you buy the bolts and which strength do they show?

          Klaus

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            #20
            Originally posted by Tony Triumph View Post
            ....are you there V Mad?
            Yes Tony, still here. Re this topic on studs vs bolts, then from a technical point of view, a long stud would have a more precise relationship between torque on the clamping nut and the clamping force. If you used a long bolt in its place, I think the bolt would twist more than a stud. This twist could have two effects: a lower clamping force for the given torque; and a twist that may unravel during service, causing a loss of clamping force. These effects may be negligible, in which case they could be ignored, but how would we know for sure?

            But what is to be gained by using a bolt if the problem is one of siezure? A bolt of the same diameter would sieze just as readily, but I guess the argument is that at least it would have a stronger head to apply the extraction force to.

            So, given all those factors, then on balance I think a reduced diameter stud is still my preferred choice, but only just. But cost is another factor I havent considered. How much would a set of suitable bolts cost, and where in the UK can we buy some?

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              #21
              Originally posted by V Mad View Post
              ........and where in the UK can we buy some?
              You can check with Fastenal. If they don't have them, they can order them.
              John

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                #22
                Jack.jpg
                I thought it time for an update on the current progress. Although four studs, broken and otherwise, still remained firmly in position on each head, it was decided to attempt to force the heads up on the remaining studs. With hindsight it would have been best at this point to remove the exhaust manifolds before applying any hydraulic upward force.
                So, having bolted VMad's 'L' shaped plates to the inlet manifolds and positioned an assortment of hydraulic jacks between the two cylinder heads, high pressure was then applied to both heads. It's hard to know how much tonnage was being exerted between three jacks, but I would guess beyond four tons. Eventually, the right cylinder head started to move up the studs. After an inch or more of space had now formed between block and head, the manifold was coming into contact with the steering shaft and so it became clear at this point sawing through the four studs was going to be necessary. With the help of VMad and Colin taking it in turns with me, we soon sawed through the four studs using an Irwin mini hacksaw. Then we just lifted the RH head straight off. Now we will refit the head and bolt it firmly down to remove the LH cylinder head. The picture shows the gap created before the sawing commenced.

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                  #23
                  That's put some stretch in that timing chain !!!
                  '72 Manual O/d Saffron Yellow

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                    #24
                    It's ok David. There was a Stag specialist present

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                      #25
                      I reckon if you had just got the Oxy-Acetylene Cutter in there and just sliced through those chain guides and chain, it would have come off easier
                      Last edited by milothedog; 16 March 2015, 15:52.
                      Wise men ignore the advice of fools, but fools ignore the advice of wise men sigpic

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                        #26
                        Plasma cutter would have been better than the gas axe, but the removal of 2 cam bolts less messy....

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                          #27
                          Ah yes the wonderful studs, I would like to know which bunch of clowns decided it would be a good idea to use a nut on a stud, and to cut a screwdriver slot in the end!!. Sounds like an idea thought up by one of the political parties or The Pub Landlord!!. Jonathon

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                            #28
                            image.jpg

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                              #29
                              Putting aside how this happened, I would like to understand more about timing chains.
                              From the photo the head was lifted about 1.5" at the chain end, this equates to stretching the chain about 3". We have not heard if the chain broke. If it didn't, a stretch of 3" in 34" is impressive. I would have thought a few % would be more realistic. How much are the so called pre stretched chains stretched??
                              If a chain can take this sort of abuse, it stops a lot of worries about longevity, do we know make of chain used?
                              Last edited by KOY 23; 18 March 2015, 13:04. Reason: Figures amended.

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                                #30
                                Looking at that photo closely, my guess would be the head has come up about an inch, making the stretch, if it did, more like 2 inches. My guess is the tensioner must have failed in some way, the chain cut or snapped or the movable guide was not well clamped and it moved. I find it incredible that the chain behaved like chewing gum, and if they do please tell me the supplier so I can avoid them.

                                Not meaning to be critical, why was the chain not disconnected in the manner stated in the manual rather than leaving it connected to the cam? It can't have helped the lifting process!

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