Can anyone tell me if the finer thread easyout is stronger because it has more threads biting into the broken bolt or is the course thread stronger because it bites in deeper. Or are they much for muchness?

The best one is the one that'll remove the broken bit of the bolt. I've also got a set of straight flute ones, that i find to be successful.

Now this just a theory but,
I think the finer thread ones may "screw" into the hole in the bolt and expand the bolt making it tighter in the hole it's in.
The coarser ones may still screw in but are leass likely to expand the bolt.
Just by opinion

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I was going to get stuck into a broken bypass fitting in a MK1 S head. I have 3 kits and they only go up to No.5 which bottoms out. I will have to buy a No.6 before I go any further.

they're scary.... they're really hard, so very brittle... if it's broken because it's rusted in, then they can easily shatter and leave you with a much bigger problem. Whenever I have something I can't get out, I do what Dr Mini says and drill it out, then put a tap through it....

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Hope its not too rusted in. The head was recoed about 15 years ago and the bypass fitting was cut off for some reason. Do you use a 9/16" drill and a 5/8" UNF tap?

I haven't used the finer thread ones to judge their success, but had good results with the coarser ones; they really bite themselves down into the offending bolt as they wind it out. I've also tried the straight fluted ones mentioned in a previous reply, with little success.

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I have some straight flute ones, you knock them in after drilling appropriate size hole, also in kit. Seems to be better for softer metal bolts.

try snap-on sr40k 4 piece set, drill hole belt in and turn out

Left threaded drill bits! I had an ezyout snap on my during the week and was a crap time trying to get it out. Ended up drilling out and putting a threaded stud with double locknuts instead of replacing the bolt.

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If it was a Alloy head https://www.youtube.com/watch?v=fqZYgReuywM

and probably not the best way to doo it but still https://www.youtube.com/watch?v=jnF9_LotHCU

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Nick

http://www.ausmini.com/forums/viewtopic.php?f=3&t=86675

that's what I'd use, the chart says 14.4mm drill for tapping at 81%, 9/16" is 14.3mm, so yeah, that'd be a good choice. It shouldn't touch the sides and as long as you can get the tap to start, it'll peel it out nicely

or ask Dr Mini

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If you really must use an easy out, drill the biggest hole you can get away with and use the biggest one you can fit. If one breaks off in the stud, you'll never drill it out.

I'm waiting for a left hand drill set to arrive. I've heard many people say that just the heat and vibrations from drilling the stud is often enough to loosen it, and it will screw out on the drill bit.

Here's hoping!

Tim

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With respect to the fine v's course fluted ezyouts, I think the same as Phil850... the fine thread will be more likely to expand the fitting into the thread.

That said, I have broken enough ezyouts in my time that I would incrementally drill the fitting out and clear the thread. I did this earlier this year, and even used the correct 'special' tap to clean the thread out.

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I think i will give the easyouts a miss this time. I don't have the correct size anyway so i might as well spend the money on a tap. Thanks for all the feedback.