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Discussion Starter · #1 ·
Anyone know what the correct alternator pulley diameter should be? On another post I have going I am having high rpm issues and believe it is the signal I am getting from my alternator. It was swapped out with a Pep Boys special before I bought the truck. If I can get the correct size, I will go boneyard shopping to find one so I can see what rpm's I really am turning.
 

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62MM is the correct size, measured at the place where the belt rides. If you find a source for one, please post it. Mine is not the original and the tach reads about 14% high.
 

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don't know if this will help, but www.alternatorparts.com has different sizes(6 groove serp) 2-7/16,2-3/8 one of these should be it 62mm worked out to 2.4in. guess need to be to big side.
 

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Discussion Starter · #4 ·
Cool thanx. I found a 2-7/16" = 62mm pulley for $15 at this site. Now I can fix my rpm problem.
 

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A better fix might be to recalibrate the tach (if possible). A smaller pully (higher indicated RPMs on the tach) does give increased charging capability at lower speeds. On the Hummers (which do not use an alternator driven tach) a smaller pulley does give a slightly better low speed charge rate (nice when winching...)

If you do change the pulley check to make sure the belt is not too tight...
 
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