Helicoil question

[AR67GTX]

I looked all over Mcmaster-Carr website and couldn't find any double-ended studs that were different sizes on each end.

I was wrong on two counts - first, thinking back it was female thread adaptors I was looking for a couple weeks ago for a sprinkler nozzle fix. And two, what I found was at another site other than McMaster-Carr eventually. Sorry for the mis-information.

 

[SublimeSixpack]

Depends on how their put in, and the fit. On my 906 heads, every stud hole was too loose. Drilled, and tapped each hole, and when I installed the helicoils, painted the outsides with Stud-loc. Let that cure, and coated the stud threads with #2 Permetex. Not even a drip.

Those two-sized studs mentioned, are called step-studs. Used all the time on radial engines.

Glad your method worked out. Just curious though, are they still leak free?

 

[moper]

I just go the next size up and either use a larger bolt (I don't care about drilling) or find the stepped studs.

 

[miller]

Just curious though, are they still leak free?

Yes. This is probably the third set of heads I've had to operate on, that way.

 

[SublimeSixpack]

Yes. This is probably the third set of heads I've had to operate on, that way.

That's good. I have a friend that had his 906 heads done at a machine shop, they used heli-coils and he has leaks. I'll pass this info. along to him.