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  • 1965 - 1973 Classic Mustangs -General/Talk-
  • Classic Mustang Specific Tech

Pully for 3G alt swap

  • Thread starter Thread starter ForceFed70
  • Start date Start date Sep 18, 2009
F

ForceFed70

That's why they call it "dope"
Founding Member
Dec 6, 1999
4,818
1
69
BC Canada
Sep 18, 2009
#1
  • Sep 18, 2009
  • #1
Where did you guys get the v-groove pully from? My stock pully is the wrong size (shaft size is too small) and all of the 3G alts in the junk yard had a 6 or 8 rib pully.

Thanks!
 

ddonaca351

Active Member
Dec 1, 2002
2,055
1
48
Camas Washington
Sep 18, 2009
#2
  • Sep 18, 2009
  • #2
Any good machine shop should be able to open up the stocker to the right dia.

Or most of the pulley companies (march, etc...) should have one that will work.

Just measure the stock pulley and use that measurement to get the right one.
(down in the grove, the outside dia is irrelevant... although larger o.d. is better for anti-flyoff at high rpm)

When in doubt you can go slightly larger to slow the alt and free up a little bit of power: ala - underdrive pullies
( a 3g alt will probably make more power at idle than your stock alt did at redline )
 

Tim65GT

Active Member
Feb 24, 2004
1,149
2
39
West Texas
Sep 18, 2009
#3
  • Sep 18, 2009
  • #3
How many amps is the 3G alt you plan on using?

I got the pulley with my alt from these guys:

RJM Injection Tech Alternator Accessories & Parts

I have a a serpentine setup, but they also sell a dual V-groove because it will slip with a single belt if the alt is over 100Amps. (mine did - when I had a 130A 3G)

 

cramer

New Member
Jul 13, 2007
8
0
0
Sacramento, California
Sep 24, 2009
#4
  • Sep 24, 2009
  • #4
Picked up my dual v pulley from a local Napa auto store and had the old one removed at a local Kragens since they had an impact wrench...then put the new one one had them tighten it and then retest the alternator.

Marc Cramer
 
F

ForceFed70

That's why they call it "dope"
Founding Member
Dec 6, 1999
4,818
1
69
BC Canada
Sep 24, 2009
#5
  • Sep 24, 2009
  • #5
cramer said:
Picked up my dual v pulley from a local Napa auto store and had the old one removed at a local Kragens since they had an impact wrench...then put the new one one had them tighten it and then retest the alternator.

Marc Cramer
Click to expand...

Did you specify a make/model/year, or better yet do you know a part #? The NAPA guys in my neck of the woods are useless unless you know the part# or can tell them exactly what year and engine combo of the vehicle it came stock on.

Thanks.
 

chris66dad

Member
Dec 19, 2008
167
0
17
Benicia California
Sep 24, 2009
#6
  • Sep 24, 2009
  • #6
I got mine with my chromed 100 amp 3g alternator from here:
http://cgi.ebay.com/ebaymotors/CHRO...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories
Give John a call @ 559-978-8043 or email A-1truck@sbcglobal.net
 
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