Exhaust stud hole needs help

[dave]

Hi all,
I have an exhaust stud hole in my cylinder which is about half gone.
I removed the exhaust stack and part of the helicoil is showing and upon
further investigation, it looks like about half of the threads holding
in the helicoil are gone. The stud and the nut came in one piece. I
removed the helicoil since it isn't doing its job anymore and I'm
curious about the next course of action.

The helicoil is a 5/16-24 and it should have been a 5/16-18.

I suppose I could put in a new one and hope the remaining threads will
hold the coil and stud, but I'd rather fix it better.
I'd also rather not pull the cylinder and have the hole filled and retapped.

Any good suggestions out there? Some sort of threaded insert?


Thanks

Dave

[Stealth Pilot[_2_]]

On Fri, 05 Dec 2008 20:49:54 -0500, Dave > wrote:

>Hi all,
>I have an exhaust stud hole in my cylinder which is about half gone.
>I removed the exhaust stack and part of the helicoil is showing and upon
>further investigation, it looks like about half of the threads holding
>in the helicoil are gone. The stud and the nut came in one piece. I
>removed the helicoil since it isn't doing its job anymore and I'm
>curious about the next course of action.
>
>The helicoil is a 5/16-24 and it should have been a 5/16-18.
>
>I suppose I could put in a new one and hope the remaining threads will
>hold the coil and stud, but I'd rather fix it better.
>I'd also rather not pull the cylinder and have the hole filled and retapped.
>
>Any good suggestions out there? Some sort of threaded insert?
>
>
>Thanks
>
>Dave
>
>
sad to think that it is time to make the faithful old cylinder into a
door stop but that is the likely outcome.

exhaust studs are made in about 10 sizes of oversize to counter the
wear in the cylinder threads but having a helicoil negates all that.

go shopping for a new one (cylinder).

Stealth Pilot

[stol]

On Dec 5, 6:49*pm, Dave > wrote:
> Hi all,
> I have an exhaust stud hole in my cylinder which is about half gone.
> I removed the exhaust stack and part of the helicoil is showing and upon
> further investigation, it looks like about half of the threads holding
> in the helicoil are gone. The stud and the nut came in one piece. I
> removed the helicoil since it isn't doing its job anymore and I'm
> curious about the next course of action.
>
> The helicoil is a 5/16-24 and it should have been a 5/16-18.
>
> I suppose I could put in a new one and hope the remaining threads will
> hold the coil and stud, but I'd rather fix it better.
> I'd also rather not pull the cylinder and have the hole filled and retapped.
>
> Any good suggestions out there? Some sort of threaded insert?
>
> Thanks
>
> Dave

Since this is the "homebuilt" group you can use this trick,,,
Warning,, not legal on certified stuff.. First the bad news is you
will be able to fix it but it probably involves pulling the cylinder
altho if you are a contortionist ya might get lucky. All you need is
a "step stud" there is one size on one end and different on the
other,, Dorman is one company that makes those and I am sure there are
others. You can also build one at home if you have a lathe. Since the
helicoil is shot the hole in the cyl is close to the right size to tap
to 3/8-24 or even 3/8-16. Just get the hole tapped with decent threads
and screw in the step stud and you are good to go. There is also the
idea or using a 'Keensert" but you will still have to retap the hole
too...



Tailwinds . Ben,,,,