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monomanx Samba Member
Joined: September 25, 2004 Posts: 715 Location: Southeast
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Posted: Thu Aug 01, 2013 12:52 pm Post subject: Technical question re Porsche 12V generator |
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Hello,
I do not own a porsche but I am using a Porsche 12V Generator (smaller diameter) on a 6V generator stand in a VW to maintain the small body generator look. I had it rebuilt a number of years ago and the charge light always has been on at idle. At speed it does charge.
Is there a smaller diameter pulley available to turn these faster? The Pulley I have is a stock 12V pulley from a VW.
Thanks in advance
Chris |
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saddlesore1 Samba Member
Joined: November 20, 2006 Posts: 548
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Posted: Thu Aug 01, 2013 2:21 pm Post subject: |
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I have the same issue. I spoke to the guy that rebuilt the generator and he says there is no issue. It is annoying yes but not to worry. He said he can adjust the regulator to make it go away when at idle but there will be no purpose. At Idle the generator does not charge sufficiently anyway. The only thing he would be doing is adjust the point the light comes on. |
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bbspdstr Samba Member
Joined: May 11, 2012 Posts: 494 Location: PA
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Posted: Thu Aug 01, 2013 4:30 pm Post subject: |
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I know very little about VW pulley diameters, but from the few VWs I've had, the generator pulley was much larger in diameter than that of a 356.
The adjustment of the regulator is a true possibility, but obviously the regulator has to be of the adjustable type.
I have done quite a few 12v 356 conversions over the years, and the 'problem' most often seen is the one described here, even with the 'proper' 356 pulley parts. The most success in getting the red light out, sorta, at a ~900rpm idle, is the transistorized regulator available through most 356 parts vendors and it's most likely a VW replacement anyway.
The least problems have been with originally 12v generators and the most with the 6v>12v conversion units using VW parts....but none of the results are predictable...it's in the rebuild and the 'mix' of parts used with it.
Most of those units that balk make the red light go out at about 1500 rpm +/- and unless you have the headlights and wipers on at idle for a long time, the idiot light is merely annoying or distracting...unless the battery is weak to begin with. _________________ Bruce Baker
www.356restoration.com |
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monomanx Samba Member
Joined: September 25, 2004 Posts: 715 Location: Southeast
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Posted: Fri Aug 02, 2013 9:43 pm Post subject: |
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thanks for the input on this issue. It is interesting that the mixture of parts could be the culprit. Regarding the smaller pulley thought, could a generator be over revved?
i do note that at around the 1500 rpm range the light does go out.
thanks again for the help!
chris |
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Tall Bloke Samba Member
Joined: October 07, 2005 Posts: 234 Location: UK>Ohio>UK
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Posted: Wed Oct 08, 2014 7:02 am Post subject: |
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bbspdstr wrote: |
I have done quite a few 12v 356 conversions over the years, and the 'problem' most often seen is the one described here, even with the 'proper' 356 pulley parts. The most success in getting the red light out, sorta, at a ~900rpm idle, is the transistorized regulator available through most 356 parts vendors and it's most likely a VW replacement anyway. |
bbspdstr - when you mention the transistorised regulator- does this refer to the solid state regulator ? see image - If yes - would the 30 amp or 38 amp be the correct part ?
Thanks . _________________ -------------------
All of 30 horses ! |
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sam_w Samba Member
Joined: March 07, 2002 Posts: 1479 Location: Petaluma, CA
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Posted: Thu Oct 09, 2014 7:44 am Post subject: |
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Interestingly I have info on the early 356 generator pulley.
My 63 singlecab with a 1600 engine was getting too hot when I drive on Interstate 5 with the temperature at 105 degrees outside!
This was because I put in a 3.88 Ring and Pinion to get 3000 RPM at 60 MPH.
With high outside temps the fan was not going fast enough, so I got a 356 pulley from Pelican parts, this is 10% smaller in diameter that a VW generator pulley, and the engine now can run at 60 MPH in 100+ weather.
Generators never generate any output at idle and that is one of the reasons that alternators have taken over, they give output at lower RPM. _________________ 63 singlecab
73 thingster
74 Thing |
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Tall Bloke Samba Member
Joined: October 07, 2005 Posts: 234 Location: UK>Ohio>UK
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Posted: Thu Oct 09, 2014 10:05 am Post subject: |
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Sam-W
What diameter is the 356 pulley, so I can check what I have ?
Thanks
Tim _________________ -------------------
All of 30 horses ! |
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sam_w Samba Member
Joined: March 07, 2002 Posts: 1479 Location: Petaluma, CA
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Posted: Thu Oct 09, 2014 11:20 am Post subject: |
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I really do not know, I can go and measure it, I did have to go through many different belt sizes.
I will measure & take piccies. _________________ 63 singlecab
73 thingster
74 Thing |
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Tall Bloke Samba Member
Joined: October 07, 2005 Posts: 234 Location: UK>Ohio>UK
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Posted: Thu Oct 09, 2014 1:18 pm Post subject: |
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Hello Sam
The pulley OD on my converted to 12v 356 generator is 99mm (4 inch) - assuming this is a 6 volt VW pulley ? _________________ -------------------
All of 30 horses ! |
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sam_w Samba Member
Joined: March 07, 2002 Posts: 1479 Location: Petaluma, CA
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Posted: Thu Oct 09, 2014 2:13 pm Post subject: |
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I measured mine and it is 3 9/16ths or 3 3/4 " _________________ 63 singlecab
73 thingster
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Tall Bloke Samba Member
Joined: October 07, 2005 Posts: 234 Location: UK>Ohio>UK
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Posted: Fri Oct 10, 2014 4:49 am Post subject: |
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Thanks Sam - I will try if that works for me. _________________ -------------------
All of 30 horses ! |
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