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duncanstokes256

Last Hurdle - Heli Coil In The Tank?

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Typical - last hurdle, putting the ali tank back on and the petrol tap threads on the tank seem shot almost to the point where the tap pushes into the tank missing the threads altogether. Last few threads do bite but not enough to hold the tap to the tank.

Any advice anyone?

Heli coils any good, I've never used them so open to advice (pros and cons).

Tank is very dry inside and paint in v good condition so don't really want to weld up the hole and re-drill.

Help, any thoughts?

Dunc

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Duncun,i'm not a fan of helicoils.been a engineer by trade i've come across a lot of them over the years.they are ok as a temp job but i allways advice people to use the steel insert instead.these are ready available of e bay or any engineers suppliers.

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I can offer a few tips having used helicoils for years for certain applications.

The primary thing with inserts is to drill and tap parallel. This is more critical when components are bolted together verses inserted like a fuel tap but still good practice.

Its obviously harder to stay parallel when using a hand drill and hand tapping verses a mill bed, say.

You can always make a drill guide for hand drilling with great success. It can be as simple as a small block of timber with a flat face that then has the drill you use "drilled through timber block at 90 degrees to flat surface" by using a drill press for timber guide.

I've even made metal ones that get clamped to job and the block guides the drill through the thread to be repaired. You can also make another guide block for the tap and keep it parallel to repair thread or perpendicular to repair thread. Once well started you can remove guide and tap away...

You are probably going into ally or maybe steel in the tank? Either way use a lubricant to tap, creates a better thread surface.

Check with EZlok about compatibility with automotive fuels and the sealant used on the insert. Just in case... they may specify a different insert to standard when sealing fuels?

Some fuel taps may be tapered thread? Some may be flat shouldered and have a washer to seal? I have not seen the one you have... if has sealing washer its critical you use a drill/tap guide because if you are not perpendicular to sealing surface the washer will be cocked and possibly not seal.

Loctite make some great fuel union thread, sealers. One they have goes off like a two-pack epoxy and it seals good enough for high performance, off-shore, race boats.

Take ya time, there is no hurry! Like my old teacher used to say... measure twice, cut once!

Mags

Edited by mags
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There is nothing wrong with inserts,been using Cross and Recoil inserts for years,they are a good permanent fix.With your fuel tap as said you must make sure the insert is dead straight into the hole.If you have not used them before, just find someone experienced to do it for you.

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I've used plenty of helicoils and they've never let me down even in really hard wearing locations , like sprocket bolts threads in magnesium hubs. Id recommend them.

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Some great info, thanks all. I've certainly learnt something new - carbon steel inserts look like a great future solution.

In the end I took the tank and tap to a local indy bike shop, asked for some advice and he fitted a heli-coil while I waited, all for a tenner - how about that!!

Now need to re-flush the tank for any last fragments of swarf.

Of course the petrol tap tightens up exactly 180degress from where it should so will need a thin washer to sort.

I think that's about it - will post some pics of the finished bike soon.

D

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Hello I had a 350 barrel hellicoiled worked ok but I had to get it done again. It draged the coil out when I took the head off. I snaped 1off the studs off the bottom end had to have it drilled out and hellicoiled. That did work fine.

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