<VV> Do Gen Pulleys Lose Their Grip?

[corvairs]

Tony wrote:

>At 1439 05/19/2004 -0400, goofyroo@excite.com wrote:
>
>>I have a modern (7127) alternator installed on an early with a custom
>>
>bracket.  It uses the original generator pulley.  The system works fine until
>you put a really, really heavy load on the alternator (AC with condenser fan),
>then the voltage starts dropping.  
>
>Not entirely unexpected.   What *is* the rating on your alternator?   And how
>much does the voltage drop?    
>
>
>>An alternator rebuilder, whom I know and trust, says the unit checks out
>>
>fine.  (I had replaced the diodes, regulator, and brushes in
>troubleshooting.) 
>He says the belt is probably losing grip.
>
>Do you hear any shrieking or chirping noises?   One way is to simply watch the
>alternator with the engine running with a heavy load while you rev the
>engine.    However, it's gonna have to be slipping a LOT to drop the voltage
>enough to become an issue.   
>
>>When you look at it, on a Corvair the belt only grips the gen/alt and idler
>>
>pulley over about 1/4 of the pulleys' circumference.  Unlike on other engines,
>where the belt contacts about 2/3 of the pulley.
>
>However, a lot of people have been running standard alternators with AC and
>other accys all on at the same time and no real problems.   
>
>
>>Any thoughts on what might be done to improve the grip?  I have tried
>>
>tightening the belt, using a "cogged" belt, and loosening the belt, to no
>avail.
>
>
>It's been my experience that the belt needs to be relatively loose in order to
>stay on the engine unless you never rev the engine to any degree...  better
>luck is had with Powerglide cars than manual shift cars.   
>
>I'd work with a smooth polish on the pulley and use a cut belt...  IF the
>alternator pulley is actually slipping.   The standard cut belts will bulge
>slightly when pulled around a corner and grip the pulley tighter.  A cogged
>belt will not.   The cut belt on a polished pulley is gonna give you the
>tightest grip you can expect without excessive belt wear.    
>
>I'd also check out the wiring, especially the heavy wire from the
>alternator to
>the battery + terminal.   If that wire has a less than adequate connection on
>either end, voltage drops could become evident, along with hot connections.
>   
>
>There are sharper people in here than me, who likely will have better
>information for you but this is what I've seen in my times.  
>
>
>tony..  
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