OOPS MY BAD, I thought I covered it all below but I forgot to mention something else which may help....
Yet another reason why typical old farm tractor coils have the LV primary winding resistances they have (6 volt around 1.2 to 2 ohms, 12 volt 2.5 to 4 ohms) IS TO LIMIT THE AMOUNT OF CURRENT THE POINTS CARRY AND SWITCH SO THEY DONT BURN PREMATURELY !!!
And that max current is typically somewhere around 4 amps
THEREFORE in a 6 volt system the total LV primary resistance (coil + any ballast) is 1.5 ohms as 6/1.5 = 4 Amps in a 12 volt system the total LV primary resistance (coil + any ballast) is 3 ohms as 12/3 = 4 Amps
Again a typical old farm tractor coil DOES NOT HAVE A DISCRETE STAND ALONE RESISTOR TUCHED AWAY AND HIDDEN SOMEWHERE INSIDE THE CAN the LV primary winding resistance is a function of the wire used, its resistance per unit length, and the length.
On a 12 volt tractor if the coil plus any ballast used doesn't have around 3 ohms total resistance the coil will overheat and the points burn prematurely. Of course extreme high charging voltage can also cause overheating as can leaving the ignition on when not running
YOU HAVE TO INSURE YOurCOIL (since you have no ballast) has at least 2.5 to 4 ohms LV primary winding resistance or it can overheat. If it has more like 1.2 to 2 ohms IT NEEDS AN EXTERNAL BALLAST RESISTOR
I think I covered most of it now lol post back any questions
Upload one or more videos to your post. Photo filesizes should be less than 300K and Videos, less than 2MB. Formats allowed are gif, jpg, png, ogg, mp4, mov, and avi. Be sure to use filenames without spaces or special characters, and filetypes of 3 digits lower case.
We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today. [ About Us ]
Today's Featured Article - Tractor Profile: Farmall M - by Staff. H so that mountable implements were interchaneable. The Farmall M was most popular with large-acreage row-crop farmers. It was powered by either a high-compression gas engine or a distillate version with lower compression. Options included the Lift-All hydraulic system, a belt pulley, PTO, rubber tires, starter, lights and a swinging drawbar. It could be ordered in the high-crop, wide-front or tricycle configurations. The high-crop version was called a Model MV.
... [Read Article]
Latest Ad:
1964 I-H 140 tractor with cultivators and sidedresser. Starts and runs good. Asking 2650. CALL RON AT 502-319-1952
[More Ads]
All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy
TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.
