Scary sparking - need help

So I have got my daughters kombi running and registered but it hasn't been driven very far (around the block) and after changing a fuel pump the other night I noticed when giving the 1835 a good rev there seemed to be sparks shooting out of the alternator stand which frightened the crap out of me seeing as a bit of fuel was spilt on engine during the pump changeover.
The alternator is a bosch 55 amp unit that is pretty old but I threw it on the reco motor to replace the old generator. I doubt if I have the wiring wrong because its charging normally, but I wonder, if something was stuffed inside the alternator would it be possible for it to 'shoot current' through the body of the alternator and down the stand?
I had a type 3 fuel pump on it originally to get it running but noticed one night that the alternator and pump body were almost touching and because it was dark I noticed a spark jump across when revving. So I put on a new correct pump and now the sparks seamed to come from where the alternator stand bolts to the engine block. It only happens when you give it a good rev so it seems to be tied with engine speed.
Any advice would be greatly appreciated.
Thanks. Greg

Sounds like a bad earth on the alternator.

Really the only slight arcing you should get is from the brushes on the spinning commutator inside the alternator. Earthing the alternator just means the arcing will continue inside the alternator case.
Now as you've tried a few different alternators then I'm wondering if these are externally regulated alternators?

When I used this alternator last on my dual cab it had 2 wires that go to a Bosch re51 regulator and it is set up the same now in this motor. So I might check the earth and try again.

What condition are the bushes in? But shouldn't cause that either.

grinderman wrote:sparks shooting out of the alternator stand

grinderman wrote:sparks seamed to come from where the alternator stand bolts to the engine block.

That isn't brushes.

Having voltage spark like that means that the voltage and or/current being generated is far bigger than it should be as this would explain how the sparks can jump so far. So try a different regulator. No scratch that as, if memory serves, the alternator must be matched to it's regulator due to differing way manufacturers design the way the voltages etc are created.