Helicoils?

[Daytony]

Anybody use helicoils for repairing damage holes in the exhaust side of the head? I twisted 3 studs off and the machinist only drilled and tapped and they look like crap, I think they will leak.

What size helicoil kit would I need for this?

[supercrackerbox]

I've got several helicoils between my cars. I've used them on the flywheel bolt holes in the crank, intake and exhaust threads in the head, valvecover bolt holes, and probably a few other places. Well worth it, works like a charm.

Intake/exhaust threads: 8mm x 1.0
Valve cover bolt holes: 6mm x 1.0
Transmission bellhousing: 12mm x 1.5
Flywheel bolt holes: 11mm x 1.0 (kinda hard to find)

The top three sizes will do 90% of the threads on your engine.

[Daytony]

Thank you very much!

[cams1021]

When using helicoils, I like to use loctite in additon to staking the coil at the bottom.. not sure of the heat capacity of loctite grades but its something to consider.

-Cameron

[Mike M]

Intake/exhaust bolts/studs/nuts are all 8x1.25 - I have a head disassembled right behind me and I was chasing threads on them already. Don't use 1.0

[TurboBaron]

And I might add, always... ALWAYS remember to stake the helicoil !!
I have seen many people use them and always blame them for failures only for me to come along and back the helicoil out by hand. Some people don't know you have to stake them. Just FYI.

[Daytony]

Quote:

Originally Posted by Mike M Intake/exhaust bolts/studs/nuts are all 8x1.25 - I have a head disassembled right behind me and I was chasing threads on them already. Don't use 1.0

Thank you for clearing that up lol. I went to the parts store and they looked at me funny, all they had was 8x1.25

[Daytony]

Quote:

Originally Posted by TurboBaron And I might add, always... ALWAYS remember to stake the helicoil !! I have seen many people use them and always blame them for failures only for me to come along and back the helicoil out by hand. Some people don't know you have to stake them. Just FYI.

Can you elaborate on this? I don't know what you mean by "stake" them. I can take a guess, use a punch and tap the sides of the helicol when installed to keep them from backing out? just a guess lol.

[supercrackerbox]

Quote:

Originally Posted by Mike M Intake/exhaust bolts/studs/nuts are all 8x1.25 - I have a head disassembled right behind me and I was chasing threads on them already. Don't use 1.0

Crap, you're right, I aplogize for the mistake.

[cams1021]

Quote:

Originally Posted by Daytony Can you elaborate on this? I don't know what you mean by "stake" them. I can take a guess, use a punch and tap the sides of the helicol when installed to keep them from backing out? just a guess lol.

Staking means just hitting the end of the installation tool with a hammer to bend the last coil outward to seat into the material you're installing the helicoil into.

Theres a small clam-cut in the last (bottom) ring of the helicoil for when you stake it. Just run it in until it bottoms out, then hit the back of the installation tool with a hammer.

-Cameron

[Chris Faulk]

Quote:

Originally Posted by Mike M Intake/exhaust bolts/studs/nuts are all 8x1.25 - I have a head disassembled right behind me and I was chasing threads on them already. Don't use 1.0

Valve cover bolts are 6mm x 1.00

[Chris Faulk]

Quote:

Originally Posted by cams1021 Staking means just hitting the end of the installation tool with a hammer to bend the last coil outward to seat into the material you're installing the helicoil into. Theres a small clam-cut in the last (bottom) ring of the helicoil for when you stake it. Just run it in until it bottoms out, then hit the back of the installation tool with a hammer. -Cameron

My machinist friend has always used a high-strength Lthread-lock liquid on the outter portion of the heli-coils. He also will insert the heli-coil just far enough down to be flush with the top surface. At that point he'd tap the install tool and it'd break off that piece used to screw in with.

I never have messed a heli-coil up with this method.

[Aries_Turbo]

anyone have a pic of "staking"? the install tool that came with mine from napa is plastic and it seems like it would get messed up wehn doing what you describe... Also, when you install them, does the little horizontal piece go in first or last? I just used a helicoil for the first time a few weeks ago. thanks

Brian

[Chris Faulk]

Quote:

Originally Posted by Aries_Turbo anyone have a pic of "staking"? the install tool that came with mine from napa is plastic and it seems like it would get messed up wehn doing what you describe... Also, when you install them, does the little horizontal piece go in first or last? I just used a helicoil for the first time a few weeks ago. thanks Brian

You can't stake anything with that plastic POS you have. The tool you need is like a T-handle tool.

I've had to make-do with the plastic thing and it always boogers itself all up pretty quickly.

Here's a picture of the tool we're talking about. CLICK HERE.

The horizontal piece should go in first...and if the hole is deep enough then you can stop flush with the object being worked on. If you Loctite the heli-coil and let it dry you won't have any issues. Stop the heli-coil flush and then let the loctite set. Then when you tighten your bolt down it will break the horizontal piece off as it goes down. I've done this many many times with no failures or heli-coils unscrewing.

[Aries_Turbo]

ahhhh I gotcha. yeah the plastic piece is a pos. I'll prolly do the loctite thing in the future. all i ever use helicoils on are tranny pans usually.

Brian