MGB Manifold plug

[Carlbanan56]

Hi, I have a potential problem with the intake manifold on my MGB -1975. A plug bolt on the manifold won't fasten correctly. The bolt is loose and when trying to fasten the bolt will spin forever. It seems that the threads inside the manifold are torn (check the attached files). I am guessing this i pretty bad and that the bolt has to be airtight. It looks like the threads deeper down are fine. Could I just get a longer bolt? Is there any other way?
Young and inexperienced

 

[mezy]

longer bolt and a copper washer should do the trick,
the only other alternative is a helicoil, (ptueeee), hate the things, not the best putting a steel thread into alumimium,
but it is a steel bolt afterall. or you could tap it out and put a bigger bolt.

 

[Carlbanan56]

Thank you!
Do you know what threading size the bolt has?

 

[YakkoWarner]

That actually looks like its designed for some sort of fitting that has threads further down on the body. Is this a bolt you ever have any intention of removing again in your lifetime (or reinstalling whatever the original fitting was)?

 

[bobhustead]

I fear that if you do any drilling or other tooling, other than chasing existing threads, you will be putting metal crumbs into the intake. Its only aluminum crumbs, but still.
Bob

 

[Carlbanan56]

I tried removing the holding plate for the choke and throttle cable and this made it possible for the bolt to reach the new threads. So getting a new bolt that is a few millimeters longer should work.