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Discussion Starter · #1 ·
just looking to see who is running what alternator pulley w/ what lower. my first lower was a 6# and the alt went out a couple weeks later 100 miles from home. then swapped the the 4# and its been fine for 3 years w/ a 3.2 alt pulley. some have said it was just coincidence w/ my bad stock alt.

so...

what lower?
what alt?
how long been running the setup?

I want to try a 6# lower again but dont know if I should keep the 3.2 or swap to the next one up on the alt.
 

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Blower Whine Junkie
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618 Posts
I ran no alt pulley with my 4lb lower for a year with no problems. Honestly the only reason I swapped to a 3.2" was because my battery was dead and I decided since I was pulling the alternator to check it anyway I'd swap the pulleys. I think Dwight ran his 4lb for a long time without an alternator pulley.
 

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un1230/Whipple3.4/ Teksid
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2,448 Posts
I run a 130mm alt pulley with my 6lb lower cog belt system

mofasta
 

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952 Posts
I am running a 6lb with a 3.7 Alt I think. I twas the same one that I had when i ran an 8lb with stock upper.
 

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3.2 alt here, with 4lb. been that way for about 3 months and 2500miles. no issues as of yet.
 

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I ran no alt pulley with my 4lb lower for a year with no problems. Honestly the only reason I swapped to a 3.2" was because my battery was dead and I decided since I was pulling the alternator to check it anyway I'd swap the pulleys. I think Dwight ran his 4lb for a long time without an alternator pulley.
Yeah, I did a 4 lb llower with stock alt pulley for 14,000 miles and have been running a 6 lber with a 3.2 for another 8,000 or so now. Have about 34,000 on original alternator.....Knock on wood!
 

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what is everyone's voltages hanging at while cruising around during the day and at night with headlights on? Just want to get an idea.
 

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Discussion Starter · #10 ·
seems like everyone is all over the place...lol....I guess Ill just try it on the 3.2 and see what happens.
 

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6lbs lower with a 3.5 Alt. when I had the Eaton!

10lbs lower with a 3.9 Alt. when I had the KB!

KK
 

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I run a 3.2 with my 4# lower. With the alternator being as shitty as it is, i figured it couldn't hurt.
 

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L&M build in progress!
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3 & 4# lowers/ 2.76 for 45K. No issues. Still on stock alt, alt pulley and stock battery. I'm sure they will go out now that I said that out loud.
 

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When I had my 6# lower on I ran the one size bigger than suggested pulley size. The 3.7".

I sold the lower but I still have the alternator pulley if anyone needs one.
 

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889 Posts
Stock Lower=2.6 Alt Pulley
2 Lbs Lower =3.0 Alt Pulley
4 Lbs Lower =3.2 Alt Pulley
6 Lbs Lower =3.5 Alt Pulley
8 Lbs Lower =3.7 Alt Pulley
 

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I ran a 3.2 with my 8lb lower for about 2 years when my alt took a dump. I run a 3.5alt now with 8lb lower, simply because with my 3.5upper/8lblower/3.5 alt pulley, the belt sizes jump way too much. I currently use a 83in belt that fits perfect.. the next belt size up that I could fine was a 89in belt.. nothing inbetween. But this was about a year and a half ago.. my alt is still working. If it ain't broke, don't fix it.
 

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I ran a 3.2 with my 8lb lower for about 2 years when my alt took a dump. I run a 3.5alt now with 8lb lower, simply because with my 3.5upper/8lblower/3.5 alt pulley, the belt sizes jump way too much. I currently use a 83in belt that fits perfect.. the next belt size up that I could fine was a 89in belt.. nothing inbetween. But this was about a year and a half ago.. my alt is still working. If it ain't broke, don't fix it.
what size belt should i get with 6lb lower 3.7 alt and 2.93 upper stock pulleys not 100mm's im thinkin 80in belt
http://www.metcomotorsports.com/supercharger_belt_length_recommendations.htm
 
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