stud holes that are too big to tap

[nightracer91]

OK. I am in a bit of a situtation. I finally got my new head torn apart and cleaned. I decided to pull out the exhaust manifold studs. One was already broke, and another hole was a bit stretched. To make things worse, when I was drilling out the broken stud, I accidentally drill at a bit of an angle which opened the hole too much. So now I have two exhaust manifold stud holes that are just a little too much open to tap nicely. What should I do?

 

[Vtec_Killer]

I'd take it to a machine shop and see if they can do anything with it. If not you might have to get a new head. Good Luck.

 

[nightracer91]

Well a guy I work with said something about a helicoil* But I don't know how to do that.

 

[fourreGsixty3]

Here you are...I know its for the valve cover but it should give you an idea>>> http://www.plymouthlaser.com/heli.htm

Dustin

 

[nightracer91]

Hey Thanx man!

 

[liam_mcmahon]

i had the same problem and a helicoil worked perfectly

 

[SBstar]

http://www.diamondstarmotorsport.com/mainthardware.shtml

The helicoil may work great but here's another option, you will have to drill out your bolt holes in the manifold to make it work but its an option. Use the 10mm exhaust manifold studs.

 

[nightracer91]

http://www.diamondstarmotorsport.com/mainthardware.shtml

The helicoil may work great but here's another option, you will have to drill out your bolt holes in the manifold to make it work but its an option. Use the 10mm exhaust manifold studs.

What are the factory studs? 8mm?

*Nevermind I see it now.

 

[fourreGsixty3]

Yes they are all 8mm for 1Gs, and the outside ones on 2Gs are 10mm.

Dustin

 

[SBstar]

I replaced a couple of mine with the 10mm's and it works great, but the helicoil sounds like a great idea as well.

 

[fourreGsixty3]

shane replacing the little 8mm studs with 10mm studs sounds like a good idea, more sturdy of bolt, and hopefully less prone to snapping off flush when trying to take them out.

Dustin

 

[nightracer91]

Yeah, I priced a heli coil insert kit yesterday. You get the tool, tap, and 8 coils for $30. The tap is a M10x1.25. For that though, I can do SBstars's idea and just tap them all to M10x1.25 with my tap, and spend around $30 for the 10mm studs and nuts.

 

[SBstar]

If you use the 10mm studs don't forget to drill out the holes on the manifold to be big enough

 

[autonut]

Ive done the 10mm replacements and they were int the end better than the helicoils cause you dont have to worry about them coming out if you take it apart again.

 

[1997GST]

depends on the angle that you drilled them at, but you may actually have compromized threads on the 10mm studs as well. I would suggest mocking up whatever your solution may be (bigger studs or a helicoil setup) and then mixing up some JB weld for a permenant fix.

I'm not there to call the shot but it's food for thought

 

[Newlogics]

I can't seem to rememer, what is stock stud thread pitch? Is it 8mmX1MM or 8mmX1.25MM ?
Thanks guys.