While cleaning a vintage 30 Pict-1, VW 105-1 carburetor, I noticed that one of the manifold securing studs had a nut on the top side. This almost always is a sign that the threads have been stripped and that someone has put the nut on the top end so that the carburetor can be used. It is not a very effective manner for saving a carburetor. And, unsightly, as well.
This is the carburetor that is specific to 1967 Beetle Sedans and Convertibles and they are becoming more and more scarce. I turned the carb this way and that, looking for any other problems. None. It seemed unwarranted to just scrap it.
I removed the stud and found that the threads were, indeed, stripped.
I looked through my spare studs until I found one that was over-sized on one end but had the same 8mm x 1.25 threads on the other end. I called a VW specialist. He suggested that instead of drilling and tapping the hole to accommodate the over-sized stud, that I use a Helicoil. This would allow use of the original stud. Since I have a Helicoil kit of the correct size, I decided that I should do that.
Illustration 3 shows the over-sized stud, the correct 8mm stud and the stud which I removed from the carburetor, still holding what’s left of the threads.
What I did not have was a 21/64th drill bit. In order to prepare the stud hole for taping to the outside diameter of the Helicoil, I needed this special sized drill bit. I went around the corner and bought one for $6.00.
Once the stud hole was drilled to size, I used the tap which came in the Helicoil kit to thread the reamed hole.
Next, I selected a coil and screwed it onto the end of the installing tool (also part of the kit). I could feel the Helicoil “seating” itself as it screwed into the fresh threads. The coil was stretching ever so slightly so that by the time I had installed it, it was tightly secured in the new threads. I backed the installing tool out of the threads. Using a small pair of pliers, I broke off the installing tang at the top end of the Helicoil.
I selected a good stud and double-nutted it. I screwed it into the Helicoil and we were done, except for removing the double-nuts.
It was well worth the little time, money and effort that it took to save yet another vintage carburetor from the recycle bucket!