Header bolts stripped

-
7

71scamp78

Well-Known Member
Joined
Sep 28, 2014
Messages
1,341
Reaction score
312
Location
terre haute indiana
Well header header gasket was leaking and I went to put bolts back in and the very front one and very back one are stripped which doesn't make sense they threaded in and out several times no issues. This is on my 69 GTX with a 440 just wondering if you guys have any recommendations for fixing it in car I don't wanna take the head off. I don't think I can get a drill in there to drill them out..wasn't sure if I could attach a drill bit to something I can hand crank or not. Thanks in advance
 
You can try small pair of vise grips. If you can get a dremal in there and flatten part of the bolt for the vise grips to grab.
 
What about a right angle drill? I have a nice 3/8 battery Milwaukee that has plenty of power and is small. I could take a picture with some measurements if you would like.
 
You might be better off trying to go to the next metric size since metric bolts are sizes that are in between SAE bolts. This way there's very little to drill out of the hole. Sometimes the stripped SAE bolt hole is the exact size (tap drill size) for the next size metric bolt. When you drill out the hole you have to make sure and keep the drill bit 90 degrees (vertically and horizontally) to the head surface. Even a slight angle will make the hole not square to the head and will also make the threads crooked. They make small 90 degree drills, you can't do it by hand!!!. You can go to the next size SAE bolt but then you're going to have to cut out more metal and then maybe drill out your header holes. When you tap the hole you also have to keep the tap at 90 degrees to the head surface. Also, once you drill out the hole (Tap drill size) put a small chamfer at the entrance of the hole so that the tap starts with less force. The chamfer will also help to center the tap in the hole.
If I lived close by I would do it for you.

Treblig
 
Sometimes the bolts aren't long enough and only catch the first 4-5 threads and pull them out. I had that happen once on a 360 and I ran a thread tap in to clean things up and found some studs long enough to make use of all the threads available in the heads. Problem solved. Made it easier to hang the headers too.

BTW: if you do take the heads off and heli-coil them make sure and seal them with high temp sealer or them may leak.
 
The silver powdered stop leak will also seal the bolts/threads...
 
well thanks for all the help . I just gor home from work think I'm gonna pull the head real quick and take to my buddies engine shop he gives me a good deal might as well have him do the whole head helicoil
 
Ok got the head off and at the machine shop gonna have all the holes done. Good news is the guy I bought car from said previous owner had engine freshened up but wasn't sure what was done..well it has new pistons for one and engine looked super clean. Has a bigger then stock cam specs unknown. The heads have better springs and retainers , also new bronze valve guides..
 
71scamp78 said:
Ok got the head off and at the machine shop gonna have all the holes done. Good news is the guy I bought car from said previous owner had engine freshened up but wasn't sure what was done..well it has new pistons for one and engine looked super clean. Has a bigger then stock cam specs unknown. The heads have better springs and retainers , also new bronze valve guides..
Click to expand...

While you have the heads off, you can find out what your compression is by following this thread:

How to Check Compression
 
??? casting #'s on the heads ???
Casting # dependent, You could go from a 7/16's coarse bolt to a 3/8's fine
Allen head without thread inserts.
& I am out :)
 
You must log in or register to reply here.
-

Back
Top