NOW, you're at the FUN
aligning the center section in the exhaust housing so it doesnt rub. For one, both parts are cast iron, so they arent going to seat together as nice as other metals would due to them being so rough.
You'll have to gently tap the outter perimeter of the center section, spin the wheel, listen and
look at the exhaust wheel in the exhaust housing as it is spins.
If you hear any
noise, it isnt correct. Continue tapping and spinning untill you hear NO NOISE AT ALL
. If you get frustrated and think "Oh well, it doesnt have
to be perfect" think again. If you hear any noise at all, that means that it's rubbing somewhere. If you're spinning it by hand and it's rubbing, imagine what will happen when it's under boost and spinning faster than you ever could by hand....now you see why it has to be perfect.
One way to control the turbine wheel possibly scraping the exhaust housing is to port/clean up the exhaust housing. A die grinder would be easiest, but die grinders can move pretty fast and you can apply a good amount of pressure, especially if you get overzealous.
I'd stick to a dremel just because you're only trying to clean up the imperfections rather than PORT the exhaust housing.