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I hear you on that.

I tend to file the stud flat, centre punch the stud then use a lathe centre drill in my pistol drill to get the hole central then use shortened 4 and 6mm drills to stop the wandering and flexing.
I normally clamp the head to the bench with a G cramp so I can use both hands on the drill.
I clean out the remainder with an M8 taper tap then run a plug tap in to make sure.
It's a risky way of doing the job because as soon as the hole wanders your screwed.
I don't have the cash to have the studs spark eroded and to be honest most places wont touch mag alloy because of the potential fire risk.

Heads are ~356 aluminum, not mag alloy, no fire risk.
(I suppose the head would have to be worth the machining expense, many T1 cores probably aren't)

vw cases and transmission cases are mag alloy, but the studs usually screw right out of mag....

Piledriver wrote:Heads are ~356 aluminum, not mag alloy, no fire risk.
(I suppose the head would have to be worth the machining expense, many T1 cores probably aren't)

vw cases and transmission cases are mag alloy, but the studs usually screw right out of mag....

Ooops my mistake.