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Just stripped a thread, advice needed
Irony - 29/9/14 at 03:41 PM

Managed to build my entire kitcar without stripping a thread until today! Its a rover V8 and the thread is on a aluminium edlebrock performer intake manifold. It holds the water system piping to the manifold. Its about m8 and there is 5mm of metal around the hole. Should I drill out and retap? Helicoil? I have never attempted either! Any advice?

coozer - 29/9/14 at 03:50 PM

Theres a feature in August issue of PPC showing how to use thread repair kits.

Looks canny easy and theres a review of 9 kits with links to buying the right bits. Price vary's wildly so shop around!

big_wasa - 29/9/14 at 03:51 PM

Helicoil....

How deep is the thread ? they come in different lengths. Standard is around 1.5D

If your local I will do it for you.

loggyboy - 29/9/14 at 03:52 PM

If its just mount for aclip? just fill it full of thread lock?!

britishtrident - 29/9/14 at 04:06 PM

At an educated guess the original thread would have been 5/16" UNC or SAE which are to all intents and purposes the same.
Thread pitch is 18tpi.
You can use helicoil style insert or a solid insert loads of kits on eBay last time I looked for not much money.

Badger_McLetcher - 29/9/14 at 04:08 PM

Helicoil it - it's quite easy. If you buy a kit it will come with a drill, a tap, the coils and the coil tool. You drill out the old threads (the important bit is to drill straight), use the tap and then work a coil in with the tool. Pretty simple and it comes with instructions.

http://www.youtube.com/watch?v=sQHRB2ElZJ0

britishtrident - 29/9/14 at 04:12 PM

quote:
Originally posted by loggyboy
If its just mount for aclip? just fill it full of thread lock?!


The permanent grades of Loctite Stud & Bearing fit might just do it. Loctite 270 or 271

[Edited on 29/9/14 by britishtrident]

britishtrident - 29/9/14 at 04:24 PM

I had a look on eBay M8 kits are a lot cheaper than 5/16". So it might be more cost effective to go metric on the repair.

907 - 29/9/14 at 05:37 PM

If there's only 5 mm of metal around the hole then I would drill 8.5 and tap M10.
(Or 3/8". don't know the drill for 3/8" We went metric in '71. The year I left school)


Paul G


[Edited on 30/9/14 by 907]

Dingz - 29/9/14 at 07:28 PM

(Or 3/8". don't know the drill for 3/8" We went metric in '71. The year I left school)

For unf it's a Q size drill, just to make it even more confusing! Pretty much 8mm.

Only 45 years ago and we still drink pints, talk about miles per gallon, 6" nails 8x6 sheets etc etc!

MikeRJ - 29/9/14 at 09:06 PM

An M8 helicoil requires a drill size of 8.3mm so there should be plenty of material left around the hole to support this.

Machine Mart sell thread repair kits that include the drill, tap and a selection of inserts if you have a store handy and need it soon, otherwise they are quite a bit cheaper to buy online.

ste - 29/9/14 at 10:10 PM

just get it filled with weld and re-drill and tap the original thread.