Moving/redrilling studs
Turbo Mini Forums

Going with a T2 in coinjunction with the factory exhaust manifold - I know some have slotted the holes on the T2 exhaust housing to take the T3 stud spacing - and others have fitted the T2 at an angle. What I would (ideally) liike to do is move the studs so the T2 fits on with no mods (I know I will need an adapter plate to taper from the T3 hole down to the T2 size). SO the question is, recomendations for moving the studs - again, I have seen pics of Matty's block with the stud holes redrilled to fit the BMW head - what's the best way? Fix studs in original holes (just screw 'em in? Loctite? Weld??) and then just redrill & tap out? Any probs with 'plugs' moving when you redrill/tap?
Thanks

1971 Austin (Healey) Sprite - running turbocharged since 1993
My Car thread: http://www.turbominis.co.uk/forums/index.php?p=vt&tid=448825

I think the only way you could do it on an exhaust manifold is to weld the holes up and redrill. On the blocks and head you can use locktite on the bungs, but with the temperatures an exhaust sees the locktite wouldn't hold up.

I can't remember exactly how far the stud holes are apart? got any pics?

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1/4mile in 13.2sec @ 111 terminal on 15psi

From memory, the T3 sized opening in the manifold flange is too large to allow t3 spaced studs to fit.

This is why you have seen some mounted at an angle.

In the 13's at last!.. Just

To Matty's point - I was thinking that the Loctite would only be needed to hold the bung in place until the new stud was in - once that is in firmly, there is less opportuntity for the bung to move. I think welding would make drilling & tapping difficult - I think the inevitable difference in hardness would make it difficukt to drill straight.
The studs need to move such that there is about 2mm overlap over the old studs.
Looks like there would be enought meat to put the T2 spaced studs in - although at first sight it's only 2mm to the side of the hole, the corner fillet means that there is more like 4mm between the stud & the T3 orifice.
I want to avoid slanting the turbo, as I really need a straight shot off the outlet to send the exhaust down the tunnel (RWD - pipe goes down next to the gearbox 7 out the bottom of the tunnel).
Thanks for the thoughts chaps - I measure up properly & keep thinking!

1971 Austin (Healey) Sprite - running turbocharged since 1993
My Car thread: http://www.turbominis.co.uk/forums/index.php?p=vt&tid=448825

True welding would be a nightmare to tap and drill. You'd have to drill the holes out alot larger to plug them, so you're not tapping into the weld

If you have access to a mill, you could offset drill the holes out 10.2mm then make up an M12 insert similar to a timesert, with an M8 thread in the middle?

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1/4mile in 13.2sec @ 111 terminal on 15psi

They would need boring out to a huge size - the far side of the original hole is about 1/2" from the centre of the new hole - a 1 inch insert would be too much (And would definitely break into the port). Looks like I will stick with the slotted holes - at least for now...

1971 Austin (Healey) Sprite - running turbocharged since 1993
My Car thread: http://www.turbominis.co.uk/forums/index.php?p=vt&tid=448825

Ah yeah thats WAY to much, I thought it was only a couple of mm. Slots seem to work well for others, so probably the easiest way to be honest.

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1/4mile in 13.2sec @ 111 terminal on 15psi

There are inserts and there are helicoils.

Helicoils require a much smaller oversize hole because it is just some kind of acurately machined spring.

I used one for a head exhaust stud (on a Honda scooter)

Rusty by nature