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Bug53
Samba Member
Joined: February 22, 2021
Posts: 704
Location: Pawcatuck, CT.
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 Posted: Sat Feb 04, 2023 12:03 am Post subject: Alternator conversion question regarding pulley |
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I am converting my engine from generator to alternator.
I see pictures of two variations.
One has a fan type pulley on the alternator and the other has a normal pulley.
The standard pulley seems the same as a generator pulley yet the belt for alternator is different.
Can someone clarify the need or omission of the fan pulley?
Thanks. |
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runamoc 
Samba Member
Joined: June 19, 2006
Posts: 5600
Location: 37.5N 77.1W
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| Posted: Sat Feb 04, 2023 11:16 am Post subject: Re: Alternator conversion question regarding pulley |
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I think that's what comes on Mexican Bug alternators
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Daily driver: '69 Baja owned 44 yrs - Plan B: '81 Rabbit Diesel LS Deluxe - Plan C: '72 Ghia
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Glenn
Mr. 010
Joined: December 25, 2001
Posts: 76901
Location: Sneaking up behind you
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| Posted: Sat Feb 04, 2023 12:46 pm Post subject: Re: Alternator conversion question regarding pulley |
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| runamoc wrote: |
I think that's what comes on Mexican Bug alternators |
The fan pulley was on Mexican engines so that's what's being sold as OE.
My 74 has a original OE pulley and it works just fine.
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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
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Starbucket
Samba Member
Joined: April 30, 2007
Posts: 4023
Location: WA
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| Posted: Sat Feb 04, 2023 1:43 pm Post subject: Re: Alternator conversion question regarding pulley |
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| The answer to your question is the alt. pulley has larger dia. than the gen. pulley thus the larger belt. The alt. doesn't have to spin as fast to charge as the gen. |
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ashman40
Samba Member
Joined: February 16, 2007
Posts: 15982
Location: North Florida, USA
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| Posted: Sat Feb 04, 2023 1:45 pm Post subject: Re: Alternator conversion question regarding pulley |
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Adding pic of the "fan type" alternator pulley for context/comparison:
I'd categorize alternator pulleys into 4 categories from cheap to expensive:
Stock pulley (clone/aftermarket)
Fan type pulley (VW Mexico/clone?)
OE pulley (German NOS or used)
Billet pulley (aftermarket) {The OE pulley and billet pulley may jockey for most expensive position}
Here's a link to CB Performance alternator pulley options:
https://www.cbperformance.com/searchresults.asp?search=EPAGP
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AshMan40
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'67 Beetle #1 {project car that never made it to the road  }
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'67 Beetle #2 {2019 project car - Wish me luck!} |
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hulbyw
Samba Member
Joined: April 24, 2021
Posts: 127
Location: Australia
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| Posted: Sat Feb 04, 2023 6:42 pm Post subject: Re: Alternator conversion question regarding pulley |
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| Starbucket wrote: |
| The answer to your question is the alt. pulley has larger dia. than the gen. pulley thus the larger belt. The alt. doesn't have to spin as fast to charge as the gen. |
So is it best to change pulleys when you convert to alternator or doesn't it really matter. The CB site lists pulleys as suitable for generator or alternator which has me confused |
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runamoc
Samba Member
Joined: June 19, 2006
Posts: 5600
Location: 37.5N 77.1W
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| Posted: Sat Feb 04, 2023 7:24 pm Post subject: Re: Alternator conversion question regarding pulley |
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| Quote: |
| So is it best to change pulleys when you convert to alternator or doesn't it really matter. The CB site lists pulleys as suitable for generator or alternator which has me confused |
Instead of fitting the pulleys to the belt, get a belt that fits the pulleys you have. Back a few years ago I had a pulley matching issue. Stock belt didn't fit, too tight. Went back to the LAPS and bought the next 3 incremental diameter sizes larger than stock size. (same width) The middle size was what I needed. Took the other two back and exchanged one for a spare of the size I needed and got my money back on the other one. 
_________________
Daily driver: '69 Baja owned 44 yrs - Plan B: '81 Rabbit Diesel LS Deluxe - Plan C: '72 Ghia
Yard Art: 2 Sandrails
Outback: '69 Ghia - '68,'69,'70,'72 Beetle - '84 Scirocco, GTI - Pair of '02 Golfs-
VW Wiring = It's just wires |
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Starbucket
Samba Member
Joined: April 30, 2007
Posts: 4023
Location: WA
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| Posted: Sat Feb 04, 2023 8:06 pm Post subject: Re: Alternator conversion question regarding pulley |
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| hulbyw wrote: |
| Starbucket wrote: |
| The answer to your question is the alt. pulley has larger dia. than the gen. pulley thus the larger belt. The alt. doesn't have to spin as fast to charge as the gen. |
So is it best to change pulleys when you convert to alternator or doesn't it really matter. The CB site lists pulleys as suitable for generator or alternator which has me confused
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The larger the pulley on the alt. means it and the fan will turn slower thats why the bugs that came with alt.s had the doghouse cooler with a wider fan and off set oil cooler so if you have a stock fan/housing you will want the smaller pulley (it's only 1/8" smaller on the diameter) so it's not a big difference. |
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Bug53
Samba Member
Joined: February 22, 2021
Posts: 704
Location: Pawcatuck, CT.
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| Posted: Sat Feb 04, 2023 8:41 pm Post subject: Re: Alternator conversion question regarding pulley |
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| Starbucket wrote: |
| The answer to your question is the alt. pulley has larger dia. than the gen. pulley thus the larger belt. The alt. doesn't have to spin as fast to charge as the gen. |
I think the difference is that the alternator belt is wider. All the offerings I see for pulleys are for either or. |
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Starbucket
Samba Member
Joined: April 30, 2007
Posts: 4023
Location: WA
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| Posted: Sun Feb 05, 2023 1:50 pm Post subject: Re: Alternator conversion question regarding pulley |
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| Bug53 wrote: |
| Starbucket wrote: |
| The answer to your question is the alt. pulley has larger dia. than the gen. pulley thus the larger belt. The alt. doesn't have to spin as fast to charge as the gen. |
I think the difference is that the alternator belt is wider. All the offerings I see for pulleys are for either or.
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Alt. pulley circumference = 13 3/4"
Gen. pulley circumference = 13 7/16"
Now you know. |
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