Helicoil

ludwig said:

Matt Spencer said:

7811 maybe Ludyboy ..

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I admit I didn't know about that one , but is it available for the general public ?

http://tds.loctite.com/tds5/docs/HYSHM7811-EN.PDF

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Locktite 7811 is a hot melt glue. Such as would be used in a hot melt glue gun. Softening temp is 300 F. Well under the normal operating temperature of a Norton head. Jim

For just chasing threads and not cutting new ones I made a tap out of an old stock steel exhaust nut. Just clean it up good and then cut angled slots in it with a cut off wheel in your small angle grinder or die grinder. This method works for a lot of different types of threads like the left hand threads in a bicycle crank arm. If you really want to get fancy you could taper the thread and cut a relief on the back of each new cutting edge and make an actual tap - but just some angled slots with sharp edges seems to work fine for chasing. I also tried to harden the exhaust nut with a torch and some used motor oil first, but it didn't get any harder at all.
Dan.

Thanks to everyone
Phil

Ah well , if theres nothing that'd stand the temperature , putting them in wet / oiled would help them seat, id hope . I tend to use coppercoat on Exhaust Nuts .Anti Seize , temp resistant .Still tends to dissapear .

Object if helicoils were tryed would be to get them to run in free , and not get hung up , gall or catch , so Id think some lube would be imperitive. Dry youd fight them all the way , further the stickier .
Stickier the less liable to be fully seated , so impedeing the Ex Nuts . So needing a bleedy great threaded form wound in to force out so thread true to form . On a Bad Day . :?