Small hole in head at bottom of valve cover bolt!

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Also I don't think a plug/stud would fall out as it looks like the breach is in the radius of the roof, looks like you still have metal on the wall that would bottom it out.
 
Mike67 said:
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.
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It's GREAT in its element. But I have to admit, I've seen it let go in a gasoline environment. Was it applied wrong? Maybe, but it still let go. And contrary, like you, I've seen it hold up on gas tanks. Who da heck knows?
 
Mike67 said:
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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That's exactly what I was going to do. Cut down a small bolt, put a notch in it and thread it down with red loctite. It won't go anywhere and no chance for it to enter the engine. I poked around with a small screwdriver and there's really no more material that can come off.
 
JG1966 said:
That's exactly what I was going to do. Cut down a small bolt, put a notch in it and thread it down with red loctite. It won't go anywhere and no chance for it to enter the engine. I poked around with a small screwdriver and there's really no more material that can come off.
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Don’t over think this. Many heads have this happen after porting. If you want to keep bolts for a stock look, use thread sealer. Just have to remember to apply sealer every time bolts are removed. If you switch to studs you can use the new orange thread locker on the studs and they will stay permanently sealed.
Just make sure you use some kind of sealer on the threads that go in that hole to prevent a vacuum leak.
 
JG1966 said:
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.
View attachment 1715745764 View attachment 1715745765
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If you dont care for all the quick fix methods, there is nothing wrong with taking to a reputable shop and have it welded and ground back.
I have seen many heads and blocks repaired via welding it just has to be done correctly.
Good luck
 
yellow rose said:
That happens on every ported head I’ve ever done. You don’t need any sealer on it. Screw the bolt in there and leave it alone.
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Thanks Yellow Rose. I do know it's been like that for a while and I've never had an issue (that I know of). I'm gonna do something, but nothing too complicated or something that could potentially make it worse.
 
Bobzilla said:
Don’t over think this. Many heads have this happen after porting. If you want to keep bolts for a stock look, use thread sealer. Just have to remember to apply sealer every time bolts are removed. If you switch to studs you can use the new orange thread locker on the studs and they will stay permanently sealed.
Just make sure you use some kind of sealer on the threads that go in that hole to prevent a vacuum leak.
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Thanks Bobzilla. This may seem like a dumb question but let's say I use sealant and leave the hole untouched. Does that hole affect the performance of that cylinder because the wall is not "smooth"
 
JG1966 said:
Thanks Bobzilla. This may seem like a dumb question but let's say I use sealant and leave the hole untouched. Does that hole affect the performance of that cylinder because the wall is not "smooth"
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Nope. I’ve posted a couple of pictures of what the finish is like on my ports. It’s pretty rough.
 
Run a real short 1/4-20 set screw down in the hole as far as possible after cleaning it with brake clean. Then fill the hole with JB weld quick set from the port up against the set screw. I have very short set screws in the shop if needed. I am in Pa. so it would only cost a stamp.
 
JG1966 said:
Thanks Bobzilla. This may seem like a dumb question but let's say I use sealant and leave the hole untouched. Does that hole affect the performance of that cylinder because the wall is not "smooth"
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Look at the spark plug from that hole, it will tell you the story.
Post a pic of the plug.
 
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