Small hole in head at bottom of valve cover bolt!

Small Block Mopar Engine

  1. JG1966

    JG1966 Well-Known Member

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    I recently removed my 340 for some work and while going over the heads I noticed a small part of the intake runner on my left head (340 X heads) had been "punched out" along the side wall at the bottom of the valve cover bolt hole. The hole is about the size of a small pea.
    I assume somewhere in this head's life someone used a too-long valve cover bolt or something (wasn't me). I have no idea how long it's been like this. When I shine a flashlight into the valve cover bolt hole, the light comes out into the intake runner of the head. I immediately checked all of the other valve cover bolt spots inside both heads and only this one is punched out. I checked down at the valves for the metal that got punched out and it's long gone. How can this be fixed? Can I just put a dab of high temp epoxy? It's not affecting any of the valve cover bolt threads. The photo with the screwdriver, it's a very small screwdriver.
    20210601_163949.jpg 20210601_162534.jpg
     
  2. Ricks70Duster340

    Ricks70Duster340 Child of the King, widower FABO Gold Member

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    A picture showing what you are talking about would be helpful.
     
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    • JG1966

      JG1966 Well-Known Member

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      Sorry. There are photos now. It posted before they downloaded.
       
    • toolmanmike

      toolmanmike Moderator Staff Member FABO Gold Member

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      It looks like it's broken out so a extra long bolt was put in and cranked down at one time. I would just use a little sealer and call it good.
       
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      • Ricks70Duster340

        Ricks70Duster340 Child of the King, widower FABO Gold Member

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        Yeah, JB Weld should do you well on that.
         
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        • JG1966

          JG1966 Well-Known Member

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          Thanks Mike. I have no idea how long it's been like that but it's never been an issue that I know of. Do you mean sealer on the valve cover bolt to keep everything inside the head or should I try to seal the hole?
           
        • toolmanmike

          toolmanmike Moderator Staff Member FABO Gold Member

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          Just a little sealer on the bolt. Just to prevent a vacuum leak which probably shouldn't be an issue anyway.
           
        • JG1966

          JG1966 Well-Known Member

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          Thanks Rick. Is JB Weld designed to withstand semi-high temperatures? I have some in my hand right now but it doesn't really clarify it's tolerance to heat.
           
        • Ricks70Duster340

          Ricks70Duster340 Child of the King, widower FABO Gold Member

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          Has been used on engine blocks for decades!
           
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          • Mike67

            Mike67 Well-Known Member

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            If you are really worried screw a plug in from the topside until it barely peaks out. Then fill with epoxy or JBW, you will probably have to clean up or re-tap.
             
          • JG1966

            JG1966 Well-Known Member

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            Thanks Mike. I just put some JB Weld on it. Seems all good. Maybe it will improve my flow in that cylinder.
             
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            • RustyRatRod

              RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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              I don't know how the myth got started that JB Weld is good exposed to gas. It's not. JB Weld is not impervious to gasoline and that's not where you want it. I would switch to valve cover studs. They are neater in appearance and hold the gaskets on when you replace them. Coat that stud with a good coat of red high temp RTV and let it ride.
               
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              • Mike67

                Mike67 Well-Known Member

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                Every packaged I've bought said it was oil/gas resistant once cured. I've repaired sever gas tanks over the years and never had an issue.
                But that was the reason I said run/thread a plug down the bolt hole then backfill.
                 
              • Professor Fate

                Professor Fate Push the button, Max...

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                One other option would be to run a very short allen screw all the way down, Red Loctite in place. Any part that protrudes into the port, grind down & smooth it out with a die grinder or Dremel. That'll leave plenty of the tapped portion for your valve cover bolts/studs.
                 
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                • RustyRatRod

                  RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                  Their packaging has said that for as long as I can remember. That's like saying Alexandra Ocasio Cortez is conservative. It's just not true. You can ask any cylinder head porter who does a lot of it. If it worked well, that's what they would use. It's not.
                   
                • RAT ROD AL

                  RAT ROD AL I know just enough to be dangerous FABO Gold Member

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                  Well if you put JB in there and it ever comes out, BAD THINGS are gonna happen ! Just sayin !
                   
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                  • RustyRatRod

                    RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                    Now THAT I would endorse. That would be what I would call a permanent repair. ...and a smart idea, too!
                     
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                    • JG1966

                      JG1966 Well-Known Member

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                      Thanks Rat Rod. I'm surprised the piece that came out before -- whenever that was -- somehow didn't mess things up.
                       
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                      • Dana67Dart

                        Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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                        If the head is off you might want to debut the area so no more tiny fragments of metal can fall off and migrate into the engine.

                        I know you already put some jb weld on the hole, but from my thinking I would just put sealer on the VC bolt when you reinstall, that way no way for anything else to make it's way into the engine. Did you test fit a VC bolt while the JB was playable? You may have just made the hole shallower than OEM.
                         
                        Last edited: Jun 1, 2021
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                        • Mike67

                          Mike67 Well-Known Member

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                          Who in their right mind would say that???? Lol!
                          Like I said I would have done it a little differently but have never had an issue with JBW and gasoline...must be something to their claim.
                          I have a 3 wheeler that has had a blob on the bottom of the gas tank for about 10 yrs and still no leak.
                          Not saying JBW is the be all to end all but to each his own.
                           
                        • JG1966

                          JG1966 Well-Known Member

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                          Thanks Dana. Some of these guys scared me so I removed all of the JB Weld before it cured. It's back to the way it was. And yes, I checked the valve cover bolt and it went just about all the way down (enough that the valve cover and gasket would more than make up the difference).
                           
                        • JG1966

                          JG1966 Well-Known Member

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                          Thanks Mike. I repaired a tiny pinhole leak on the bottom of a gas tank with JB Weld once and it never leaked again. I'm very confident it would hold up, but I'm gonna explore my options. I'm in no hurry. I'm not getting motor back for at least a month
                           
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                          • dano

                            dano Evil Handy Man

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                            Is it just me or do those look ported in an inch or so? looks smooth then goes rough cast.
                             
                          • JG1966

                            JG1966 Well-Known Member

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                            They are just a little dirty.
                             
                          • Mike67

                            Mike67 Well-Known Member

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                            No problem, I think it would have worked also, but again there is more than one way to skin a cat.
                            There will be many good recommendations, some easy, some quick and some more involved. Pick your poison.
                            I agree with Dana7 & deburring it with a dremel or a carbide bit. I would measure the length of the hole and figure out how long of a plug you would need and either cut the end of a stainless bolt to length put a notch in it for a small screw driver to set it and JBW the threads.
                            Best of luck!
                             
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