Broken bolts PART 2

Step 1: Throw your screw removal bit set in the trash. They only work for bolts/screws that can be removed by just about any other means under the sun.

Step 2: Find a way to create a drill bit jig that will align your bit for you. A machine shop can do this cheap if you provide a good diagram and dimensions. Make one that will use two other bolt holes to hold it tight so that it doesn't move when your'e drilling.

Step 3: drill the old bolt out as large as you possibly can with a brand new zinc or carbide coated bit without drillin out the bolt hole threads.

Step 4: chase the hole with the appropriate sized tap

If you happen to mess up the threads then go get yourself a Heli-Coil kit and follow the instructions for proper installation.

Your jig should be at least 1 inch high where it alignes itself over your block so that the bit head doesn't walk. The hole in the jig should fit the bit you intend to use perfectly.

As far as the upper intake goes... take it with you to the machine shop and have them drill it out (I assume it's already removed since you're working on the lower).

When you put your new bolts in, be sure to use some thread lock. I've broken lower intake bolts off before and can usually spin them out with jsut a sharp drill bit if thread lock is used.

Hope this helps.

I assume if you broke a lower intake bolt and an upper intake bolt, the lower intake bolt is broken off in the head and the upper intake bolt is broken off in the lower intake...correct? Been there...

When I broke mine off in my head, I actually pulled the head and I believe I did actually use a screw extractor kit. One time, I used a screw extractor kit for a timing cover bolt I broke off in the block.

I assume you'll be pulling the lower off if you haven't already, so it'll be easier to work on that way anyway. I'd personally try to use the screw removal kit before I drilled out the bolt just because there's a larger chance of messing up your threads. If it doesn't work, then go on and drill it out as big as possible and go from there. DO GET STRONG BITS THOUGH AND DO NOT MOVE THE DRILL AROUND!!! Hold the drill steady and let up every 20-30 sec or so, so it doesn't heat up. Heated bits break easier. I also used some cutting fluid on my bit when I let up, i'd dip the bit in the fluid and it helps.

Good luck.

Actually, the spirals are better than the square in my opinion. I have removed several head bolts with them. The thing you may not realize is you need to center drill the bolt nearly perfect. Then incrementally drill it out until there is basically threads a bit of the bolt left. Also, you need to use a large extractor, and hammer it into the remaining bolt, it will actually dig into the bolt. Now if you're gentle, and using a rachet preferably, it should ease out. Shoot some WD on it also before.

For the lower intake to head bolt, if it is in stock type Ford heads, the end bolt holes go all the way through the head. Feel under the extension of the head at the front and you will feel the hole.

So you can use a normal rotation drill bit, and if you are carefull and lucky, go through it. If you are really lucky, it will heat up when you get nearly through it, or with a larger bit, and it will thread right out the bottom of the hole.

I had this happen on a carbed 351. Took twenty minutes to change the thermostat, and 6 hours to fix the broke intake bolts. I broke a thermostat bolt, then two intake bolts, a front and back, trying to take the intake off.

The intake bolt holes are the same arrangement on GT 40 heads, at least the two iron sets that I have.

With care and drilling, you should be able to get it so that you can use it. If the hole gets two screwed up, perhaps try a helicoil.

Last resort, is to pull the head and have a shop fix the hole and threads.