A 12 v coil will have 3 ohms to 3.5 ohms of measured resistance between the Small terminals (when not connected) a 6v coil will have more like 1.5 to 2 ohms. The variability is in the wires used (length and diameter) inside. I know of no resistors inside coils. They would produce heat and that is not desired. The resistors used on 12v coils with external resistor required are built to radiate heat. Ceramic blocks, or long wires embedded in wiring harnesses provide that heat sink. The 6v coils and the 12v coils for use with an external resistor are basically the same coil. Both will have the lower resistance. The bypass system, from the solenoid or relay, or starter switch, is designed to let the coil operate at cranking voltages between 9 and 11 volts for starting only. this gives hot spark, and keeps the resistor out of the circuit while cranking. (if the resistor was in the circuit, it would lower the voltage to around 4 volts (not reliable) as you have found out.) Jim
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 - New Hitches For Your Old Tractor - by Chris Pratt. For this article, we are going to make the irrational and unlikely assumption that you purchased an older tractor that is in tip top shape and needs no immediate repairs other than an oil change and a good bath. To the newcomer planning to restore the machine, this means you have everything you need for the moment (something to sit in the shop and just look at for awhile while you read the books). To the newcomer that wants to get out and use the machine for field work, you may have already hit a major roadblock. That is the dreaded "proprietary hitch". With the exception of the
... [Read Article]
Latest Ad:
Sell 1958 Hi-Altitude Massey Fergerson tractor, original condition. three point hitch pto engine, Runs well, photos available upon request
[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.