Exhaust Stud Heli Coil Pulled Out, Wou is me, Help! Correction Time Sert came out Options

[913B]

So the continuing saga of fitting the SS heat exchangers continue. I somehow pulled out the heli coil repair on the exhaust stud. The coil measures 9.5mm OD.
I suppose I need to re-tap the hole with a step stud.

So what size step stud should I use ?? M8 to (M10 or M11) ?
Where would I find such a stud ?
Is it do-able, drilling and tapping from under the engine ?
How the heck am I going to keep the bit and tap straight and not F/up ?

Man it never ends with old cars...... (IMG:style_emoticons/default/ar15.gif)
Thanks in advance for everyones help !!!! I really appreciate it.
(IMG:style_emoticons/default/beerchug.gif)

[HAM Inc]

Your best bet now will be to get a M10x1.5 Time-Sert or Heli-Coil kit. This will allow for the installation of a M10x M8 step stud. The O.D. of the Time-Sert/Heli-Coil will be ~12mm. This is required now that you have pulled out a M8 Heli-Coil which, as you can see, has a ~10mm O.D.

Attempts to tap for a M10 stud only (no insert) will fail as the hole is already to large for this. A M10 tap requires a .325-.340 tap.

Keep in mind that drilling to deep will punch into the cylinder itself and the head will have to come off if this happens.

Also keep in mind that the repair you are about to make is pushing the limits of material that the stud boss will support. This is the end of the road as far as repairs that don't require welding. I would be hesitant to hit the road with a repair of this sort. This may be a stop gap that buys you time, but head work is likely in your future.

This sucks for you! And it's the reason I do not install inserts in T4 heads I reman. All repairs are weld repairs with M8 threads tapped. That way if a field repair is ever required there's something to work with.

Good luck.