[Shotimes] alternator noise

[drv027]

Hi, My alternator died a few days ago and I found a used one from a 90 mtx
being junked.
I had it tested at auto zone and it passed, but 
I get a loud whirling noise. The bearings are pressed on the rotor ends ( I
took my broken one apart ). Is the way to properly separate the casing to
remove the rotor in order to get at the
Bearings : remove the pulley, four screws under pulley and then the four
case screws?
Next question : my motor craft sparkplugs are gaped at .044, would .042 or
.043 improve 
Performance? I have a lot of steep hills all around me and the plugs were
installed " without me  gaping them" ( I was told that they were pre-gaped ,
I know that I should have checked anyway ) The ride was horrible, pinging
and back firing. Your help would be Greatly appreciated !!!!
victor   91+ white mtx w/146k no modes ..yet

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