To improve access I can remove the dipstick. Also in the way is an aircon pipe; aircon has never worked and will never work again on this car, so I can get rid of that too. The studs have snapped off a little way inside the threads, making it tricky to centre punch them centrally. Is this easy work for a man who knows what he is doing?
I guess I must ask around for such a man. My son's friend Brummy the welder might know.
If the studs have sheared rather than just unscrew out with the nut they will be stuck in there pretty well.
Although I agree you can drill them out in situ the hardest part is maintaining alignment so you drill down the centre rather than off into the head.
I've made a small drill jig up that solves that problem. It also holds the drill in the correct position so centre punching the stud isn't an issue as long as you start slowly.
Good luck.
Congratulations. Could you post a pic, or describe it?
I did wonder how even an expert would do it. I have watched a few u-tube guys doing it, but the situation under the bonnet of an Omega is inconvenient.
One u-tube guy MIG welded a nut to a recalcitrant stud. That seemed ingenious in that the welding current could heat and free the bond.
I bear in mind that this car has failed MOT on emissions (lambda). We think this is due to the cracked manifold. This is why I was inclined to fit the manifold on the 7 remaining studs, hoping it sealed satisfactorily, and resubmit for MOT. It might not last as long, might crack, or might fail MOT again. The manifold seems fairly stiff, and was attached before by only 8 studs.
Like Nick W, I have removed manifolds before without trouble. This one has obviously been off before.