carburettor woes

I am a life log learner, curious, inquisitive and always ready to learn new things. Always was as an education professional and always tried to encourage these qualities in those I taught. It is important to take learning risks. Making mistakes is good learning, so long as you don't repeat make the same type of mistakes. 

So, part of me thinks "It is time to learn how to extract a sheared off bolt in a hole". 

I have the drill bits and the bolt extractors. New bolts have been ordered. 

I was given a whole host of tips from kind, generous people on various Facebook forums which I've outlined below:

"You have inadvertently bottomed the bolt in the hole and it has twisted off. Its not uncommon in a blind threaded hole". 

So I proposed drilling a small hole in the bolt after having gently tapped a centre point with a punch, then inserting a bolt extractor and extracting it carefully. I got this advice back:

"Give it a try but after you have drilled it soak it in CRC6-66 marine spray for a couple of days. Then very gently warm the ally casing before using the bolt extractor. The aly will expand more than the bolt which makes things much easier". 

"File the ragged end as flat as you can, centre punch the middle of it so the drill doesn't drift out to the edges and damage the aly, then very slow drill speed. Left handed drill bits work well, tending to unwind the bolt rather than wind it in further"

"Use easyouts - the size marked on them tends to refer to the best drill size in mm for the pilot hole. the hole needs to be a little deeper than expected for the extractor to bite".

"Could try welding a blob with oxy acetylene on the bolt and unscrewing it with locking pliers whilst it is still hot"

Other suggestions included super gluing the broken bolt and trying that. Or, using a dremell to cut a slot for a screwdriver in the sheared off section and then trying to unscrew it.

What worried me most though was that three people for whom I have huge respect - all started their advice with "take it to a small engineering shop and let them do it" .

I was told that there was a real risk that the drill bit might break off in the sheared off portion and then things would be well and truly stuffed. 

So, a life long learning dilemma. Do I follow my heart and give it a go myself, holding to the principles of its OK to make mistakes as long as you learn from them and learning new skills is important in life.

Or, do I follow my head which says "on this occasion Steve, be sensible, take up the kind offer from a real generous gent, who specialises in this kind of thing and who has offered to do it for you if you send him the offending piece".

This hurts my educational principles but I think we all know the sensible thing to do is go with the latter option. Take the knight in shining armour on white horse rescue package. 

Now, I just have to get the inlet manifold off without doing any further damage.

In future, perhaps I should just pay out the £100 to have the outboard serviced each year!