Ok Ok, it wasnt me....i just finished putting the head back onto the clubby a few days ago when i realised i lost a head bolt as most of you would know.

I couldnt source one from here so i went and bought one from an industrial bolt place around the corner for $11 (ouch) ....

t then et home to find my brother with his head under the bonnet and guess what he says...." i found a bolt that fits!!!" (from our old pile of misc bolts) i say to him that it has to be high tensile (having done engineering in school and uni i knew exactly what was goin to happen)....but being my older bro, i usually think he knows best....not this time!

Then as he said "look its tightening up all good".....

:::::::SSSNNNAAAAAPPPP::::::::::

and its another problem i have. I couldnt get the bolt out with one of those stud extractors as i think it was too tight in so i drilled it out and so now im on the look out for one of these:

http://www.elsham.pwp.blueyonder.co.uk/cx500/helicoil/

has anyone got one?
I know they can be rather expensive and all i need it for is just one threaded hole, so if anyone has got one, il pay them for an insert and to burrow the tools for a day or so??

Cheers,
John

BTW: you might be able to tell: i am soooo pi$$ed off!!!

dude I could have given you a helicoil tap, coil and inserter if I was still workin for a certain australian airline....sorry champ, I left there a few years ago.

I have a few helicoil taps, that's about it.

omg crap i could see that coming

i think you cant do it yourself, unless youre capable of lining up all the angles properly
i dont think theyre exxy at all... a threading bit and its handles arent too hard to find or buy

_________________
Inconspicuously Conspicuous
Appreciation without Depreciation
forever chasing clearer skies...

yes, i know....
anyways, anyone else have one or a similar kind of thingy???
i just had the biggest fight with my bro and he said he'd pay for the tool to fix it. I tried telling him i couldnt fix it and it'l never be the same hence i needed to buy a 1275, so he could pay for it - but i guess he's not that dumb after all!!!

so anyone know where i can get one or similar?

Yeah I had a similar problem with my engine, snapped a thermostat stud off (strangely enough a similar scenario - "hey this one fits!!"). Anyway we drilled the remains out, and retapped it (thread wasn't too damaged or anything). Just borrowed a suitable tap, nothing fancy - you can get them from a hardware store. Looking at that URL your problem is a bit worse, I'd be getting a professional to do it (there are thread-fixer dudes that do that sort of thing for a living, almost had to use one when my steering arm bolt snapped)

Anto.

I've used them before. Are you sure it wouldn't be better to just use a bigger bolt since the hole has to be re-tapped anyway?

a bigger bolt yeah if i could but the holw has to be threaded first so the bolt will stay in there.....

Anto: do u know what the people who do this rethreading are called? or where i could find them in sydney?

Yeah they are called Mini Owners!!

Head has to come off, really the motor needs to come out to do it properly- the threads must be tapped square not crooked..

My MK1 S block had 3 of the stud holes (had been stripped) tapped out to 7/16" UNC and `bull headed' studs fitted. These things are a bigger diameter stud with most of the body turned down to 3/8"- so thread at bottom is 7/16" UNC and at top 3/8" UNF.
One of them was stripped too, so I made another one- 1/2" UNC at bottom, 3/8" UNF at top.


This motor is still running- in Gareth's Mini...

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

how did you do this? did you get someone else to do it or did you do it yourself?
what do you mean by "tapped square not crooked"?
thanks for your help BTW.

when you cut a thread, it is commonly referred to as 'tapping'. Probably because it is the 'tap' that is cutting the thread.

When you are tapping a hole, you have to make sure it is going in at 90 degrees (square).

If you tap the hole crooked, you are likely to break the tap off in the hole.

You try getting a high speed steel broken tap out of a blind hole!!

We used to use an EDM (Electro Discharge Machine or something like that) to burn them out, when I was in the trade ....not that I ever broke a tap.....well I did once at TAFE....in a cast iron pump of all things!!

(Kev, Jamie put some sh!t on me for that one, I can tell you!!)

I did it myself. Anton explained how. Both of us did fitting & machining (or similar) trade so we know how to break taps, or not...

The real reason the thread must be `tapped' square is otherwise the stud or bolt will not be vertical, you won't get the head on (stud) or the bolt in if that's what yours is.

BTW I think only Oz 1098s got head bolts- all others had studs & nuts.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

its an oz 1100...

maybe it got changed to bolts when they did the work to the engine.
where can i get one of those tap sets from? (mitre 10? BBC? Harwarehouse?) or do i have to go somewhere special?

i could proly do it myself if i had the tap set.....otherwise il get someone around to do it if i knew a company or person who did it...

anyone here know how to?

drmini, do you still have the tools to do it? can i burrow them off ya and leave a deposit of some sort? A friend of mine reckons he knows how to do it but he needs the tap set. He did his apprenticeship with an industiral machine comany.

You need to decide how best to fix it, or you could end up stuffing the block.. it could be helicoiled, or tapped out bigger, to fix. If I were you I would tow it to an engine reco shop, or a Mini repair place- they have all the gear.
Threads in block are 3/8" UNC standard- helicoil fitting needs a special oversize tap.

No, sorry- I don't have taps for UNC- I borrowed them from work, back when I had a fulltime job..

If you KNOW what you are doing, and have experience fitting them, a 3/8" UNC helicoil kit is the easiest fix. You can buy from Lee Bros, Cedrays, Blackwoods, AE Baker, etc.


Then you can still use bolts. Make sure they are high tensile ones this time!

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

arent helicoils the insert threads? if so arent they weaker than getting it rethreaded using a tap and die set (proly at a bigger size)?

so the thread is a "Unified Course Thread" does this match up with any imperial or metric threads? or are they the same? sorry, i dont know much about the different threads.

If properly fitted and decent length, a helicoil insert is as strong or stronger than original.

UNC is Unified National Coarse. American thread standard.
Yes it is the same pitch (threads per inch) as Whitworth, (most sizes except 1/2"..) but the thread angle is 60* instead of 55*. Wouldn't matter for most things, but there's a lot of stress on these bolts.

If you tapped it bigger you would have to drill the head for a bigger bolt, then because the thread pitch will be different (coarser) the torque wrench setting to get the same clamping load will be different. Not a good idea.... and you would also need to drill the hole in the gasket every time.

If you really want to tap a bigger thread instead fitting of a helicoil, I would fling ALL the bolts and fit studs and nuts instead. Then you could get somebody (eg Russell Engineering) to make you a `bull headed' stud as I described above- 7/16" UNC thread at the bottom, the rest turned down to 3/8" dia with 3/8" UNF thread at top.
Maybe you can buy these studs, if not- one can be turned down from a long `Grade 8' 7/16" UNC bolt.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.