So i tapped the 8 AIR holes in the 73 cylinder head and installed the 3/8" set screws. Everythings perfect except one thing. On the last hole i broke off the darn 3/8" 16 tap! I cant get the darn thing out. It broke right flush with the head. Tried drilling a hole for an easy out and the darn tap is harder than my bit and it wont be drilled!! so now the tap is in there flush. I did manage to grind it level with my cutoff wheel BUT, I dont know how to get it out! I could leave it ini there but its not threaded on all sides. It has flutes on it. I filled it with JB weld and I guess I have to leave it in there and hope the JB holds. What else can i do??? What do guys use to drill out taps. What kind of bit and center punch will be able to cut it? Thanks for any help you can lend. Gary
No drill bit I know of will drill out a tap. I've had some luck with carbide endmills used in a milling machine, but theres no way that I know of doing that in the car. You could try a small punch to try to turn the tap backwards by hitting the flutes. Keep moving around the diameter of the tap, hit each flute a couple of times, then move to the next one. You also might find a tap extractor. It has little "blades"? that fit down into the spaces between the flutes. If the tap is not too deep in the hole, sometimes you can just get mad and hit that sucker and bust it into small pieces and get them out that way, but I don't know how to keep the pieces out of the engine. Sorry I don't have better suggestions. Scott
pretty much any tool you use to try to get out the broken tap is softer than the tap. if you have the room, bang the tap back and forth, hopefully breaking up the chips so you can turn it out with a tap extractor. you will need lubricant in the hole. other than that, e.d.m.ing the tap is the only other way. btw, awhile ago i saw somebody selling a neat little basic homeowners e.d.m. machine. wasnt bad on price. but i cant remember where i saw it. a couple of things about tapping existing holes. you need to address the hole with the tap drill to clean out any garbage and rust. rust will kill a tap regardless of hardness. you also need to use top quality taps. preferably guntaps. a normal 3/8-16 tap has 4 flutes. ok for mom's stuff. a 3/8 guntap will have either 2 or 3 flutes. they have more webbing which makes it stronger. also you need to be straight with the hole or suffer the breaks. do you or did you use tapping oil? dry tapping will get you in trouble. another item for your toolbox is to buy cobalt drill. not hi speed or carbide. to tell if its cobalt, the tang end will be stepped down in diameter. at pratt whitney aircraft, my dept did testing on tooling. yeah, thousands of holes....boredom. got more questions, email me
thanks a lot. ive got 7 of 8 holes successfully tapped and plugged. that one with the tap is flush with the head and I filled in the flutes with jb weld. hopefully it will grab onto the threads and the flutes and it should be about 3/8 deep and hopefully will block the exhaust from coming out of that hole. Im putting it back together tomorrow. I dont have time anymore, i need my car. Its easy enough to take the manifold off again if it leaks it shouldnt be too bad. It i can hear it i will have to take the manifold off sometime and try the tap extractor. I already tried the center punch trick but couldnt get it to budge. Someone suggested welding a nut on top with a MIG welder but I havent got one anymore. Id like to get one in the future. The other option is the walton tap extractor with the blades as was metioned. Ill have to find one of those and possibly try that. Doubt it will work now that JB weld is all up in there. If the head has to come off to have it fixed, ill just put 70 heads on there and be done with it.,, but then ill have to do the same thing to the 73 block... maybe ill get lucky and the hole will be sealed. One guy said he just pressed tight fitting bolts in there with JB weld and it was good for 20 years. But bolts dont have flutes... ..... so close and yet so far..
http://ssgedm.en.made-in-china.com/product/nMFmUhqAbgWO/China-Removing-Broken-Drill-EDM-VLA-.html this is one portable edm machine. i cant find the one thats simpler. yet. walton does make the best tap extractor. but its no match when the tap is solid in the hole. you need to help loosen it up. trying to remember which acid you can use to help dissolve it. tough getting old....
When I break off a tap like that I usually end up getting a punch and BFH. shatter it and clean it up.
I had decent luck getting a broken tap out with a carbide burr in my dremel tool. Got one with a little ball on the end and went slowly, letting the burr sink itself into the tap. I worked myself a slot into it and turned it out with a big screwdriver.
I've seen this done with some success, as long as the broken bits don't fall into the engine and cause harm. I currently have a broken drill bit stuck in an exhaust manifold bolt hole. Bruce
It is actually easy to get it out of a cast iron head. A tap is made of a steel alloy, which melts at a lower temp than cast iron. Someone skilled with a oxy-actylene torch can melt it right out of the head and not even damage the threads in the head. I have done the same trick to get broken studs and fittings out of exhaust manifolds. If the head is off of the car, it is even easier--just take it to a good welding shop and they can melt it right out of there.
Before you make the situation worse, take the car to a good machine shop, they are experienced at this sort of thing,,,, i am not talking about an automotive machine shop ,,, I am talking about a general machine shop....
what happens to the molten metal from the tap when it is liquified? how do they keep it from flowing into the hole and solidifiying in the head somewhere? Thats wild. What is BPH? and is it possible I could crack the head if I start beating on the tap with a punch? I would love to beat on that tap, just afraid I would damage the head.
You can only do the melting with a torch trick if the hole is oriented such that the molten metal will flow out of the hole. If the head is on the engine and the top of the hole is facing up, you can't do it--either have to take the head off or turn the car up on its side!
Can you start the engine up and let it warm up and then pour cool water on the tap?????? might be worth a try....
I have removed several broken bolts etc from manifolds heads etc. Find or make a washer the exact diameter of the broken off bolt/extractor. Then weld the washer to the bolt. Dont weld it to the head..... After successfull weld of the washer, weld a bolt to the washer, and simply turn the bolt out with the new bolt head. Jon
