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'H' coil resistor ?

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Neighbor has an H that he restored it runs for a while then dies. I told him i would look at it and it seemed like the coil was getting hot. he ordered a new coil from Stieners and it does the exact same thing does it need a resistor in line or do these new coils have a built in resistor?

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need more info than that... is it a 12 volt conversion with the original 6 volt coil?

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IIRC  there was a post about this occurring  with a crossed wire or reversed ground from what battery is.

IIRC resistor is on the output side to save the points

have been to sales where they have blown up,intentionally letting key on and or reverse cables ,help not knowing or.......wanting it to sell low.

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Resistor goes on hot side to lower voltage or you can buy a coil with internal resistor. When running a resistor you could do like factory vehicles and take power of starter solenoid to give full 12 on fire up to help starting. When key released it goes back to resistor. If positive ground positive on coil goes to dist. If negative ground you hook the minus side to dist.

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A little added info, just in case. The only time a ballast resistor is needed for the coil is if you have converted to a 12 vdc battery and 12vdc alternator and are still using the original 6 vdc coil. The ballast resistor is then needed to drop the 12 vdc to 6 vdc. The 6 vdc from the ballast resistor is then fed to the 6 vdc coil and all is well. If you feed a 6 vdc coil 12 vdc it will get hot and over time will burn out. Now the added info, just in case part. Many times confusion occurs when 12 vdc is seen at both ends of the ballast resistor. Many times it's concluded that the ballast resistor and/or coil is bad. But, 12 vdc on each terminal of the ballast resistor is normal when the points are open, magnetic field of coil is collapsing and producing high voltage ignition spark. When the points are open the ballast resistor is out of the ignition circuit and indicates 12 vdc at each terminal because when out of the circuit it is nothing more than a length of open wire. When the points close it puts the ballast resistor back into the ignition circuit ( closed points provide negative potential to the ballast resistor if ground is negative.) Now you will show 12 vdc being fed into the ballast resistor,  and at other terminal, (output) about 6 vdc. This reduced 6 vdc voltage is now fed to the 6 vdc coil, energizing it to the saturation point of 6 vdc waiting for the points to open so the negative potential will be removed from the ignition circuit, causing the magnetic  field to collapse , creating high voltage ignition spark.  A good ballast resistor with my multimeter checks about 3 ohms. If your ballast resistor is bad (open) and (in) the ignition circuit and (12 vdc is applied) you will show 12 vdc input and 0 vdc output at all times, points open or closed.  I have been confused as to if I have a 6 or 12 volt coil. They are either old and all info worn away, or brand new with no marking on the coil other than no ballast resistor required. A 12 vdc coil will indicate 2.5 to 3.5 ohms across + and - terminals. A 6 vdc coil will indicate 1.25 to 2.0 ohms. I have found open coils ( indicates 0 ohms) still able to start and run the engine, but produces weak spark at spark plug. So if your engine starts a runs don't assume your coil is good, check it. Now back to coils. I bought a new 6 volt coil that was marked no external resistor required, on it. But when installed the tractor ran like crap. Only when I re -installed the external ballast resistor did the tractor run like a champ with good spark. The coil was indeed a 6 volt coil BUT did not have a ballast resistor built into it. So I guess the No External Resistor Required marking stamped on my new coil was referring to. If you are using a 6 volt system no external resistor is required on this 6 volt coil. Buyer beware.

 

 

Hope some of this helps

 

Tim 

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It is still 6 volt system i have 6.53 volts at battery and only 5.23 at coil so i ran a jumper wire direct from battery to coil. The tractor now runs but surges under load, like the governor is bouncing, but it's not. They coil gets so hot you can't touch it. the ohm meter says 1.1 on a bare coil.

if i apply 6  volts to the hot side of coil what should the ignition side read? I am just trying to help this kid out it's his first tractor and he is getting discouraged it died on him in the middle of memorial day parade.

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 1.1 ohms on bare coil should still be ok for 6 volt coil. Plus side of coil to distributor, neg side to ignition switch. Both my farmalls were converted to 12 volt neg ground when I bought them so I don't have any first hand knowledge on 6 volt positive ground. From what I've read if it is 6 volt positive ground, + side of coil goes to distributor. 5.23 vdc at coil should still give you a good spark. But on something this old everything is suspect, even the wiring and it's insulation. Another problem I've read about is if battery is allowed to die the 6 volt generator could reverse it's polarity and cause strange problems. If it were mine I'd connect my timing light to the plug wires and when it starts to die see if timing light goes dead or still flashing. Goes dead, ignition problem, keeps flashing, fuel issue. Also would connect to each of the spark plug wires as it's dying if time allows and look for steady flash. You can also connect timing light to coil output wire and look for same indicators as plug wires. This will tell you if coil breaking down when it gets hot. On both my H and Super M the coil cases if metal will get almost as hot as the engine it sits next to. A temp. gun would let you know if it's hotter then the engine. If it is warmer then the engine you have a problem. Be methodical and work through each wire and component. Points condition and gap would be good checks also. Until you can prove it stops supplying sparks to the spark plugs your primary problem could be fuel related. My H surged a little till I cleaned the carb and got it properly tuned. I know the surging can also be caused by weak springs on the mechanical advance unit.On my M it was stuck in the mid range of it's allowed movement so when I pointed the timing light at the 1st timing mark on the crankshaft pulley the timing never moved. From low idle to high idle.

Double check or maybe someone with a working knowledge can verify + side of coil goes to the dist./points. 

Good Luck

   

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1 hour ago, from H to 80 said:

It is still 6 volt system i have 6.53 volts at battery and only 5.23 at coil so i ran a jumper wire direct from battery to coil. The tractor now runs but surges under load, like the governor is bouncing, but it's not. They coil gets so hot you can't touch it. the ohm meter says 1.1 on a bare coil.

if i apply 6  volts to the hot side of coil what should the ignition side read? I am just trying to help this kid out it's his first tractor and he is getting discouraged it died on him in the middle of memorial day parade.

With points open battery voltage. With points closed 0 volts. With engine running about half voltage.

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Have you analyzed the rest of the iginition system yet? Has he got fancy resistor spark plug wires? Points gapped correctly?

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i did not check the wires i do know the are new,i filed and reset the points checked spark plugs and i tried a timing light but mine will not work with 6 volt.

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If you have a spare 12 volt battery of any kind, I use a spare motorcycle battery. Connect the timing light + & - to that just to power the timing light. With the sensor connected to a plug wire or coil wire it should flash when the 6 volt coil provides the high voltage to the wires and the plug sparks. That works with my 12 volt timing light, hope it does with yours too.

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Coil was wired backwards, my fault I had no idea . That solved the problem with coil getting hot but it still had the surging when I loaded it up  and the lights were flickering. The amp meter showed  0,so I polarized the generator it then showed a pretty good charge.  About two minutes later it dropped to 0 charge again the lights flickered and it almost died.

What I finally found was a bad connection on the hot wire on the starter button I fixed that and everything is good.

I had no idea on the + going to distributor on a positive ground tractor. Thanks for all the help and Paul says thanks as well. The amount  of knowledge shared on this site is amazing.

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Congratulations and job well done. Hope your young friend has a better time at his next parade.  

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