18 replies to this topic

[nakes]

What should I do? please see the post in the link below

http://www.theminifo...dpost&p=2197079

[yellowmonster]

You'll have two options (as you already mentioned yourself):

- either you'll have to tap new thread (which will have to be somewhat bigger than before, like 3/8" -> 1/2"),
- or insert a Helicoil

I personally think the latter is best...

Edited by yellowmonster, 15 August 2011 - 09:20 AM.

[Dan]

Which one is it? The front end one is not particularly stable to begin with because there's not a lot of meat around it, it often punches through into the water jacket. A Helicoil or Threadsert or some other thread repair method is your only option really, if you take it out larger how are you going to get a head stud to fit? Try a Helicoil to begin with but you might find you end up needing to get the original hole filled and redrilled if it is the front end stud because the enlarged hole might well start to break out.

[bmcecosse]

As above - depends which one it is. Can you show us a pic ? If possible I would go for the drill and tap oversize - fit a plug - then drill and tap that to take a new stud. But if it's too near the edge........... there was a good reason BMC only had a smaller diameter bolt in the 11th hole in the Cooper S block.

Edited by bmcecosse, 15 August 2011 - 11:52 AM.

[nakes]

The image isn't my engine but the arrow shows which bolt thread stripped...

[Dan]

Yes that's the front stud, the weakest one. Did you torque in the correct order? This stud should be torqued last so it's not pulling the head down as it's tightened.

[nakes]

So heli-coil is what I need to do??

what if I just treat it as a 9 stud and ignore the fact that I have 2 extra studs in the block? what's the real benefit of having two extra studs?

[nakes]

Yes that's the front stud, the weakest one. Did you torque in the correct order? This stud should be torqued last so it's not pulling the head down as it's tightened.

Yes I torqued the 9 main studs.. then left the two extra studs for last... it didn't even feel as if it was very tight when I heard a click that wasn't the click from the wrench... I first thought the bolt snapped but then slowly turned it out to find that thread pulled out the block...

I have another 11 stud block that's probably in better shape than this one... but I really don't want to have to rebuild the engine.... Again... this one's been standing for a few years... but only did around 100km before it stood...

[Dan]

Then give the Helicoil a go, if it holds it'll be fine. Although given the position maybe a Threadsert would be better as it wouldn't be inclined to start pulling out if the metal opened up and relaxed around the outside of it a little. I'd check with a good local engineer or MRA Minis for clarification on that if I were you.

[Cooperman]

I've had to Heli-Coil several 11th bolt holes over the years. The thread is 5/16" UNC
You will probably find that the existing hole is already right through into the water gallery, so simple not fitting that bolt would not be possible in such a case.
Just drill, tap and Heli-Coil, then fit the correct bolt - if necessary with a bit of instant gasket sealer if it's through to the water way. Torque it to 25 lb.ft and the job has been done properly and is not 'bodged' in any way.

[bmcecosse]

The turbo engine didn't have the extra stud and bolt. It's really not necessary. Easiest thing would be to plug the hole and forget about it.

[nakes]

ok, I got a thread insert which was recommended by the bolt place that sells it... they said it's better than a heli-coil for use on the block... the thread tap seemed a bit pricey so gonna first see if someone I know has one the size that I need...

What's the best way(with the engine still in the car) to drill and tap straight?

[Ethel]

Any reason why you can't glue a stud in with loctite and use a nut? Would a rocker pedestal stud do?

[nakes]

Any reason why you can't glue a stud in with loctite and use a nut? Would a rocker pedestal stud do?

I have a thread maker for high heat application but I'm not sure what kind of torque pressure it will hold...

[Cooperman]

I've got a 1275 'S' block which has had the same problem and the former owner has drilled and tapped it 3/8" UNC. When I need that engine built I shall get a head stud and turn it down to 5/16" diameter except for the thread, then I'll thread the other end at 5/16" UNF and simply use a standard 5/16" UNF nut.