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| | | | Joined: Oct 2001 Posts: 578 'Bolter | | 'Bolter Joined: Oct 2001 Posts: 578 | My old Willys has a Delco alternator set up as a one wire.
If I understand correctly, the alternator energises after the engine hits a certain RPM. Is there any way to find out what that RPM is?
What is the reason to run an alternator with one wire instead of 3? Why do the conversion?
"Happiness equals reality minus expectations" - Tom Magliozzi
| | | | | Joined: Feb 2004 Posts: 29,750 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,750 | It will vary, depending on the ratio of the crankshaft pulley diameter to the one on the alternator. Because of the pulley size difference, the alternator turns several times engine RPM. There's no real advantage to doing the one-wire thing that I can see, other than saving a little time on the initial installation. It takes a specific part number regulator assembly on the 10 SI alternator to do the one-wire setup, according to the rebuilder I use for all my electrical overhaul. The others need at least a jumper wire from the charge output lead to terminal #2 on the 2-wire control plug. The #1 terminal is only used if you want a no charge light on the dash.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
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| | | | | Joined: Dec 2006 Posts: 1,464 Shop Shark | | Shop Shark Joined: Dec 2006 Posts: 1,464 | As far as determining the exact RPM it starts to charge you could do this:
attach a dwell/tach to the engine and also connect a voltmeter to the battery post of the starter (or any other "hot" spot in the system). Slowly increase engine speed while watching the voltmeter, when you see a slight jump in voltage (like say from 12.5 volts to 13.5 or so) you have your answer. | | | | | Joined: Oct 2001 Posts: 578 'Bolter | | 'Bolter Joined: Oct 2001 Posts: 578 | Now I read something that said use the 1 wire if you have an ammeter and the 3 wire if you have and idiot light. Also, the 3 wire energizes the alternator when the key is on rather than when rpm is reached.
This is all dark magic to me. Do the above statements ring true?
"Happiness equals reality minus expectations" - Tom Magliozzi
| | | | | Joined: Sep 2001 Posts: 29,269 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,269 |
If you have a one-wire alternator, go ahead and use it. I have had one as part of a 12v conversion done about 13 years ago. As HRL posted, different one-wire set ups "excite" at different RPM - mine starts charging at about 800 RPM (and then charges at all RPM after that). I use the regular 6v 1954 Ammeter gauge.
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