This has been discussed,debated and rediscussed more times than varmints eating on front porch and sleeping in the house without mention of what I'm about to say. For our purpose the subject is confined to 6 volt equipment converted to 12 volt. It goes without saying this doesn't work if it says "no resister required" on coil. I say when there's an option, go with external resister but go one step further in bypassing resister while cranking. Many oe starter solenoids have a post which supplies full battery volts to coil while cranking,if it's there,use it. Where there is no provision for bypass , a dedicated switch , push button or toggle with buzzer/light to prevent accidently leaving on can be activated while cranking. I've made this change a few times and engine invariably starts easier,most recently a neighbor's that was amazed how much quicker his old Jubilee started.
Hobo,NC
Well-known Member
- Location
- Sanford, NC
used red MN
Well-known Member
- Location
- Coon Rapids, MN
A wire from the starter feed post to the coil with a diode that is positioned so the voltage fed to the coil by the ignition switch cannot back feed attempting to energize the starter after cranking has stopped would do the same thing. There is no complicated switches, lights or buzzers required. If a diode is to complex for you electrical knowledge than use a momentary switch that is spring loaded requiring it to be held on the on position. Place it close enough to the ignition switch or start button so a free finger on that hand can push it. This leaves the other hand free to operate the choke or throttle as needed.
Fixingfarmer
Well-known Member
So I don’t own any vehicles with a resistor wire coil that is bypassed on startup and I think I might understand why people use more coils than I.
I have never on my OWN vehicle replaced a coil except for one that needed to look nice on a painted tractor.
A very quick and probably inaccurate count leads to 34 coils and coil packs on my vehicles.
I think I’ll put a 12 volt internally resisted coil on a 12 volt vehicle like was done on the good tractor from the start. I could give a care less it jumps when you breathe on the key. Simplicity is worth it too deere had it right for 10 seconds then went sideways shortly
I have never on my OWN vehicle replaced a coil except for one that needed to look nice on a painted tractor.
A very quick and probably inaccurate count leads to 34 coils and coil packs on my vehicles.
I think I’ll put a 12 volt internally resisted coil on a 12 volt vehicle like was done on the good tractor from the start. I could give a care less it jumps when you breathe on the key. Simplicity is worth it too deere had it right for 10 seconds then went sideways shortly
More fuel on the fire... many tractors have 60 year old wiring switches and 60 year old coils and dirty points..... and a very weak spark on a good day.
There was only one member here that had a problem with the 6 volt coil and a resistor. Several others said there was no problem. I can say for sure that the resistor offered from the folks at this site isn't enough. I burned a set of points in less than an hour with one of them. I have 10 volts to the distributor. That is way to much. I'm only fooling with this tractor occasionally, but I'll get it fixed eventually. For sure, a 12 volt coil will fix it. I may end up doing that.
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Voltage measurement with...Points open or points close? Was this voltage cranking or just ignition on??Did he leave the old resistor in, add a new one, did he use both resistors?, which coil?, with or without resistor type coil? 1.5 ohm coil or 3 ohm coil? Chinese points? oil on points?, As they say, a bad condenser causes burnt points?? Did points burn due to high voltage, high current, contamination, or from arcing(condenser)? Was it 2 amps, 4 amps, 10 amps or what, so we can figure the voltage drop on the resistor, and thus its resistance.. ie 1.5 ohms, or 3 ohms are common? What was the battery voltage at the battery while cranking?? BTW, 10 t0 11 volts AT THE BATTERY, can be common in older cars while cranking.. Point being (no pun intended) there are Many Many things can spoil the pot here. As I tried to point out earlier. Hard to condense the possible problems. I was researching points trying to get some American "Tungston" points a while back and in the mfg catalog it also listed the part nos of the various condensers and ALSO specified the mfd of the condensers. And surprise to me, different condensers had different capacitance... Now lets throw that wrench into the fire. But..... after ordering the blue streak parts/standard points, they came in and said " made in china" on the box. So more of the new crappy corroding problems of cheap aluminum foil beer can points.....It appears that blue streak and standard are the same company now . Could no longer find Neihoff.
Keith Williams
Member
- Location
- Wellsville, Ohio
Right with Ya Hobo!
So many ways to solve this problem.
Matching the resistance of the ballast resistor and the resistance of the coil is important.
Some of the products I looked at the last time this came up had some unique properties (e.g. variable resistance).
It might add value to let us know what you are working on.
Keith
In my 65 years of owning and driving spark ignition vehicles, I never replaced a coil. I was a mechanic at a Ford Tractor dealership for 4 years and never saw any replaced there either. Many of them had the bypass circuit that apparently just worked as designed.
Opps, I forgot one - a Model T Ford that had been converted to a distributor. The coil rusted out and the oil ran out the bottom. It may have still worked, but I replaced it anyway.
Lotta questions here. I'll just describe what I have.
I have had this 641 for 15 years. I have no livestock or do any farming with it. I've only put a few hundred hours on it in that 15 years. It was always 6 volt as it came from the factory. It always started fine - even in the winter. I put a heat houser on it and go to the woods to cut firewood.
So, a month ago or so, the 6 volt battery quit. Dead. It had an "open" somewhere - no voltage. I decided to go 12 volts as
so many have done. I did not buy the complete kit as sold on this site. I bought a couple of resistors and the alternator bracket. I used an battery that I had that was one of a pair out of a diesel pickup, so it's got oodles of CCA's. I'm still hooking up the alternator as I'm using a DR 10DN. It is mounted but not hooked up yet.
In the 15 years that I've used this tractor, I never had the distributor cap off. I had no reason to. After I hooked up the 12 volt battery, I reversed the low voltage wires on the coil because it was now negative ground. I put one of the resistors in line with the ignition switch to coil wire. These resistors are advertised as .8 ohm. I know that isn't enough, but that is what they sent to use. I started it up and it ran fine. I used it way less than an hour, and the last time I went to use it to move a wood wagon, it started normally, but then began to back fire and pop and crack and such. I barely got it back in the barn. I cleaned the points with crocus cloth and set them at .025". It started up and ran fine. I moved the wagon and parked it. I started it up again a couple of days ago. Same thing. I cleaned the points and it now runs fine - for now. I start it occasionally while working on the alternator and it runs fine. It still has the coil that came with the tractor 15 years ago.
To answer your question, the battery has 12.5 volts while running - as the alternator isn't hooked up yet - and the voltage at the distributor with it running is 10 volts. This is with a Neihoff analog volt/amp meter, not some digital Harbor Freight thingie.
I'm going to try putting another resistor in series with the one that is there. I'm pretty sure it will help, but there is no way this thing will operate correctly with the running voltage that far above the original 6 volts. I may just use a 12 volt coil, but right now, it's interesting to fool with it - "and it is a learning experience."
One more thing, I can't accurately measure ohms. The Klein meter is digital and the lowest ohm meter scale is 0-100. That doesn't make it very useful in measuring less that 1 ohm as this site describes the resistors they sell for this purpose.
Destroked 450
Well-known Member
- Location
- Harned, Ky
My volt is NAPA IC14SB coil and no external ballast resistor
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