The best way is to have a shop with an EDM machine to remove it. Barr None, thats the best and easiest way. But it may be hard to find one these days. The second suggestion is not to use an end mill, but a reamer as a reamer usually has more flutes and takes a smaller bite per tooth. They also have a chamfer on the end which helps keep from grabbing. It will try to center on the offcenter hole you have. You can make an adjustable plate to bolt across the head and that has a boss welded in place sticking up a couple of inches. The hole in the boss would be drilled and reamed to size and serve as a guide for the reamer. Best way would be to buy 2 reamers, one smaller than the other. And make it a two step process, gradually removing the off center metal. A light touch and slow pressure with a higher than normal rpm (for a reamer) and the guide positioned where the hole should be instead of where it is....should get all the bolt out. You will need to drill oversize when removal is complete and install some type of thread insert or twinsert. If you do the two step, ream boss with small reamer first and continue into the bolt. Then do it again with the finish size reamer. Get reamers that have a straight shank so they fit a drill chuck. Last suggestion is a little offbeat, but might work. Buy a couple of jigsaw blades that are abrasive coated instead of steel toothed. They would have to be narrow enough to fit in the hole so don't get wide ones. Might even have to grind a little off the backside. Make a spacer that slips over the blade so it doesn't hit the bottom of the hole and bend. Take the jig saw and stick the blade into the broken bolt hole and try to make 2 or 3 slits into the thick part of the bolt to weaken it. Then take a punch and try to bend and loosen each section. Like before, you will need to drill oversize and install an insert. Don't know if this will work, but weakening the bolt remains should help a lot. Wear safety gl***es if you try this stuff. As far as the end mill thing. It will work, but needs a milling machine to maintain alignment.....or a heavy duty drill press at minimum. The reamer suggestion is best on a drill press but probably doable with hand drill.
How we did it: Three heat cycles with Oxy/Acc. Heat the stud to red, then cover with rawhide leather (forging apron) and let cool sloooowly. After each heat cycle, douse with Kroil and let sit for a day. Bore a hole in it using using carbide burrs on a Dremel. Use the biggest easy-out that would fit. Prayer, because if that easy out breaks off in there, you're in a world of hurt.
If the hole you drilled goes all the way through the bolt as into the water jacket take an acetylene welding torch and play the flame through the hole until the bolt is red hot let cool and remove with a easyout.
This is screwy but has never failed me. I use a Torx bit. I find one that the base is at or just bigger than the hole. I grind the end square so the splines are sharp and beat it in the hole. The bolt should be softened with heat. This works way better than an easy out. An easy out pushes out as it screws in. This is like splined coupling. It just applies torque. The spreading from an easy out actually increases the torque required to get it out as it expands the bolt.
This reminds me of the saying: You’re only one broken bolt away from making a 10 minute job into a 4 hour job….
Have used this set since 1964 , doesn't work every time , but then again , nothing does ! It another useful tool in the ****nal !
is that gasket compound or the deck surface around the bolt hole? I would clean that whole area up first. looks to me like the block needs to be decked, which means complete tear down and machining. the broken bolt is just one hickup in a total rebuild.
I wouldn't drill it. Weld a large od washer to it. Then a nut to the washer. The heat from welding likely would of unsiezed it. Then simply unscrew it. Less chance of damage to the block.
Providing that have a tank (full of dielectric fluid) big enough to handle it. Most I have used are quite small. I would strap it to a Bridgeport table and explore possibilities. A carbide ball burr could get you a new start point for drilling for an insert. So would a ball end mill.
Sometimes the cheapest option is to have a job professionally done. Personally, I think that is where you are. Good luck with it. Jon
They make a Keenest for over size holes that are to big for a heli-coil .I would use the head for a guide and drill it out then remove the head and drill for a Keenest.
Hell, the more I look at the picture, it seems that the bolt is already drilled out, and all that's left is a little of the bolt from the off center drill. From the picture I'm seeing, a drift punch would peel that right out, and a chase from a tap would finish things up.
With a lot of luck, sometimes you do get lucky. I had used Keenserts and Timeserts plenty of times to salvage bad threads on tooling at work. Another option is having enough OG threads (providing the old stub comes out decently) and you can anchor a stud in place, use a nut up top.
I had a really neat magnetic jig that helped keep drill bits centered. It was made by an acquaintance of mine. I had three sizes and it was a pretty cool set-up that had marks for aligning. It would be easy enough to make, though these were pretty trick. Sadly, I loaned the kit and it never came back to me. For head bolts, I've never drilled and removed all that well. Welding a nut to replace the head always seemed to be the best... that heat helps considerably. If it were any other bolt that hasn't seen thousands of heat cycles, I mighty to drill another off center hole across from the one you have then I'd tap the holes with a hammer & punch and work it out (if there's room).
In 1964 my Dad and I were working on our Father/son project...a 50 Ford with a Merc flathead. He was drawing the head bolts down [never believed in torque wrenches] when he stripped the threads out in the block. He just drilled it out for an oversized bolt and threaded the hole....never failed.
Easy outs are far too brittle for my liking, you are in a world of poo if it busts off. I will try the Torx trick, or p*** on the info to the less fortunate. Now I treat EVERY old car piece of hardware as if it were going to break. I take my time with even the ones with good access. I use a propane torch with mapp-gas most of the time.
Good morning, start with a self tapping screw to start a new hole as a pre hole then change the size to another self tapping screw for a new drill bit, but PB blast the hell out of it,hopefully this will help, that’s if I understand what’s going on
That isn’t part of the using a self tapping screw processor, which has worked many times for me, but a magnet drill will definitely work as well just not as cheap Good luck
I would agree with many here where the the proper remedy is to enlist professional help in the way of a machinist who has the equipment to hold that block steady, and drill that hole out, perhaps oversize, and put a threaded insert in. We've all been there, and not getting it out is not a reflection on you. In fact, I posted in one of my recent threads about snapping a balancer bolt off in a brand new crankshaft, and the remedy I had was to pull the crank out of a brand new engine and have it machined out. It ****ed. But the engine runs now, so what was the alternative? In my experience, if I can't get the bolt out by welding a nut to it and turning it out, it's never going to come out without real heat. Sometimes I've gotten away with a MAPP torch, but most times O/A is the only option. This is especially the case for larger bolts where there is a lot of surface area of threads that are seized in place. When stuff rusts like that, it takes extreme measures to break that bond. Many years ago, I snapped an exhaust manifold stud off in a 383 Chrysler cylinder head. It broke below the surface so the weld nut trick was basically impossible. I drilled it on center and tried an easy out, but then that snapped, too. Realizing how screwed I was, Flatdog here on the HAMB told me to bring the head to his shop. He taught me how to take a bolt out like that with a cutting torch. Basically heat the bolt red hot with a concentrated flame parallel to the bolt, then pop the oxygen and yank the torch away. Repeat the process many times and wear appropriate safety gear. Basically, it will blow the bolt back out of the hole in a liquid form, and the steel of the bolt will melt before the iron of the block, so if you do it right, you can send a drill and tap back through it to clean it up and it's good to go. I miss that guy.
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