Was having a problem starting my Olds. Talked to an old school Olds dealer mechanic. He told me to take the negative off my battery and touch it to the alternator then put it back on the battery.
Well it worked and the car fired right up. Can someone explain what the hell I did and why it worked?!

 

I can't explain that because the alternator is already grounded to the engine just by being bolted up to it.

 

I give up
sounds like voodoo to me. Your picture appears to be a points era car, and touching the alternator with the - cable, or removing the - cable, should have no such effect. Maybe it's the time it takes, like tapping a can of soda to make it not [so] fizzy after shaking.

 

You initially probably had a bad negative cable to battery connection and in the process of removing the cable and hooking it back up cured that, thus it started......

 

X2 on the bad connection, but the Voodoo explanation sounds a bit more interesting.

 

It's the engine fairy's, that's it engine fairy's.

 

^^^THIS! You would have had the same result if you had removed the cable and touched it to your nose before reconnecting. Hint: do the same with the POSITIVE cable to clean any corrosion off of that one also.

 

I know on old Harley's, that had a generator you should "polarize" it whenever it's reinstalled by touching it with a + lead.
He is old school and probably thinks you have a generator.

 

That is standard procedure with a generator. Just not with an alternator.

 

It amazes me how many misconceptions there are as to what needs to be, how to , and when to polarize a system. But then again I am old. In any case, if the battery ground connection is removed from the battery, nothing is going to be polarized no matter where or what it is touched to.