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Model A + modern alternator


ThomasBorchers
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Hi Model A owners...and all others, of course.<BR>I have a modern alternator in my Model A. The ammeter shows a charging at higher engine speed (35 to 40 mph)with around 6 to 7 amps. When I turn the lights on then it shows a discharge with 2 amps or near to zero but not more even at 50 mph. The voltage with higher rpm is around 7.20 with lights off and drops down with lights on to 5.95 Volts. Battery is new.<BR>Who owns a Model A and can tell me if this is correct or if there is a problem and if yes, what for a problem.<P>Thomas<P>------------------<BR>Thomas Borchers<BR>Member of AACA # 004829<BR>HCCA and MAFCA

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I too run a 6 volt alt on my A. When first started my car shows around 12-14 amps,and tapers back to about 6-8 amps. (I have a taiwan 30 amp ampguage and have no idea of how accurate it is). With headlights on (halogen bulbs) It shows a charge of zero to 2 amps.<BR> What size alt pulley do you have?? Mine is around 2 1/4 inch od.<BR> Bill

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I have built well over 200 6 volt alternators,most of whlch went on Model "A" Fords.The only time I ran into what you describe was when the owner had a cheap fan belt which "bottomed" in the alternator pulley,Using a Gates 700 belt took care of the probem. Mrbuick714@webtv.net

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As input only:<BR>On a Model A, the fan belt slipping is not generally the problem. It is usually that the owner has tried to adjust it to the tension of a more modern car and not the loosness of the Model A. This easily places a strain on the Model A water pump and can even result in breaking the thing in two. I did this myself recently. I had no knowledge of how tight the fan belt should actually be, and decided to take out any slack in the thing, just as you normally do in a modern car. Big mistake! The original fan broke in two, a the pump housing broke right in half. Leave the belt as loose as it will go. If it is a proper belt for the A, then it should work fine in the pulley with a loose tension on it. If the pulley is mis-matched with a new altenator, then the belt may be slipping or not running correctly at all. The amp guage may not be correct either. If it is a cheepie reproduction, it may be reading incorrectly in the first place. the Gtes belt is very good and I don't turst Mac's as to product reliability myself. Bratton's or Snyders is much more dependable, but that is my personal opinion only. You may want to go to the following web site and post your question there as well, as it is the premier Model A site for specific questions regarding that vehicle: <A HREF="http://www.ahooga.com" TARGET=_blank>http://www.ahooga.com</A> <BR>I don't run an altenator, so I can't say more than the above as to direct experience. However, many people posting at that site do run the modified altenator set up and have direct experience with it on a Model A Ford.<BR>Huey<p>[This message has been edited by coupe1942 (edited 12-27-2000).]

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Go to the<BR> <A HREF="http://www.mafca.com" TARGET=_blank>http://www.mafca.com</A> <P>site and hit the tech Q&A section to see a multitude of questions and replys as to an altenator on a Model A. It also includes questions on the amp guage as well. I believe your specific original question may be answered there by the previous postings and replies by Les Andrews. He is a pro in the Model A field, and has written several books which are like the bible to Model A owners.<P>Huey

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Thanks Huey.<BR>I asked Robert McIntosh at Macs for the correct tension of the belt. It seems that the right tension is set when you can't turn the alternator pulley by hand.<BR>I just went to the ahooga message board and posted my problem. Got some answers but no real solution at the moment.<BR>I know Les and had some Emails with him but it seems that he is not at home at the moment because I got no answer in the last weeks.<BR>Perhaps I will change the fan belt with the belt in my fathers roadster. This car has a modern rubber belt with "teeth" but a normal old style generator. Perhaps this helps.<BR>More ideas?<P>Tom

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I will explain how my alternators work.When you start the car,you have to rev the engine a bit because you have only residual magnetism to start the charging.You can then let the engine idle and it will continue to charge. As you proceed.the alternator will at first.put the ammeter hand out of sight.trying to put back what you used to start the engine.As you drive further.the ammeter will come down to where you can read it.You will continue to get some reading for quite a while,but if you have a good battery which can and does accept a full charge,the ammeter will drop to zero-just like a late model car will do.Often times when I am driving one of my model "A"s and the hand is on zero,I turn on the lights and the ammeter will jump momentarily then right back to zero.I use 50 C.P. bulbs and they work very well.Most of my customers say the "oogah' is much better with an alternator! I have never worried too much about belt tension.if the sides of the belt are in good contact it doesnt have to be "fiddle string" tight.Have been involved with Auto electrical for sixty years and currently operate the oldest auto electric shop here in Omaha Nebraska Ralph Crisp B.C A. 2399

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