Hi folks, if I wasn’t having bad luck at the moment I’d be having no luck at all.
I don’t suppose anyone has a spare RH cylinder head kicking about? Snapped an M7 tap off deep inside the exhaust stud holes in mine, and no way of getting to it. I’m going to whip it off at the weekend and maybe try having it Spark-eroded out of there – but then I wondered if tracking down a good second-hand one would work out cheaper and easier!
It’s way too deep to get anything to the snapped surface, and being a tool steel there’s no way a drill would touch it.
“He’s King Midas (in reverse…)”, The Hollies, ~1967
Are there enough threads left to just leave the tap in there, but still get the stud in
dmc4087 Wrote:Are there enough threads left to just leave the tap in there, but still get the stud in
Thats a good thought,
Failing that have some brackets welded on to the manifold to utilise the other holes?? (not sure how well it would weld mind)
Chris
Rich, is it worth giving Martin a ring to see what he's got? He might have a spare head (or matching pair) left over from one of his engine upgrades.
FWIW, I paid £60 each for my cylinder heads, they were fully refurbed at that too
(although I think I got a bargain back then if I say so myself :wink: )
Thanks all,
Just in from an evening of battling with it. It seems spark erosion might have been the best way to get it out, and I found a place in Sheffield which would do it for £20 setup plus whatever additional costs. Not too bad, but would have still involved pulling the head off. Unfortunately there wasn;t much left of any threads at the top to use a shortened stud - not enough thread remaining for comfort, anyway.
So I thought I'd have a crack with a carbide cutter, a whole set of Dremel diamond burring tools, three or four tiny Dremel grinding stones and a set of gas bottles. Well, after four hours I now have a hole 17.5mm deep, and thankfully hasn't opened up to much more than 8mm diameter. (Stock stud holes seem to be about 22mm deep). And all the above tools are broken.
Anyway, it's reasonably straight and parallel. Next step is to tap it out to M10, and make a special 'stepped' exhaust stud which is 16.5mm of M10x1.5, then steps down to stock 7mm dia. for 10mm then 10mm of M7x1.0 to put the nut on. If I snap the M10 tap in there I'm going to go and live in a kibbutz in Australia.
So, if all goes to plan, no adaptation of the manifold!
The other thought I had re. manifold was to mill off say 4mm off the mating face of that port, then make a 4mm thick adapter plate to allow the 'spare' studs to be used, and attach that to the milled face of the manifold using countersunk M5's or similar, and weld all round the outside.
Anyway, all being well, it won't come to that - but watch this space!
I managed to succesfully extract some of another snapped stud (which thankfully was only standard mild steel, not tool steel, of course). The hole opened up a bit, but not too much to be able to helicoil it with my brand new helicoilsing kit off of that there Ebay what they have nowadays.
Thanks all!
R (no smiley available with a 'tentatively happy' expression...)
There are solid thread inserts that work a bit like helicoils but are stronger and require a larger hole in the first place. M7 helicoils would require an 8mm hole, those other things would need a 9mm hole AFAIK. Wurth sell them. (sorry, no I haven't got any spare DeLorean heads, only turbo ones which are identical but would need the injector bungs drilling and pressing in, and the dizzy hole boring out.)
Thinking about it some more - tap it out to M10 as you suggest, then take a 17mm length of M10 studding, or an old bolt and drill and tap it centrally with an M7 hole. Simples! (make sure you put SEALANT on the threads because you'll probably go intot he water jacket)
Good stuff, thanks Martin, will see what I can arrange - I'm on the borrow with getting any machining done!
What sort of sealant would you suggest, by the way?