Is JohnT still on here? other electrical guys?

JL2510

Member
I have a 720 diesel with a pony motor. I
just put an electrical tester on the
output side of the resistor that then
feeds the pony distributor. It's showing
6v, just like the wire going in. I was
thinking the resistor dropped it down to 4
volts? Or does that only take effect when
it's drawing current somehow?

I'm asking that question to ask this
question then-

I've read some posts on here in the past
about converting the pony to 12v. Not for
easier starting but for powering
accessories. John t responded that the
starter would take a quick 12v burst, at
least for a while. Then put a voltage
reducer in line to the distributor to drop
it to 6v, and it SHOULD be ok. (Asside
from changing the generator, fuel gauge,
sender, and light bulbs). I want to give
it a try. I found a 12 to 6 volt voltage
reducer, and put it on the wire that feeds
the distributor. Testing it before i hook
anything up, I see it also shows battery
voltage on both sides. I'm not going to
hook it up to the expensive pony coils
until I'm sure it's right. I know the
coils will take 6v, as I unhooked that
original resistor years ago and the pony
runs great. I'm also sure they WON'T take
12v.

So what is going on?

Thanks
 
If the points were not closed or you did not have the distributor connected when you took the reading the primary coil circuit is not loading the resistor so it has very high resistance across it so the voltage did not drop. Yes, if not in a working circuit it cannot drop the voltage. Try again with the distributor connected and the points closed. An incandescent..old style.. light bulb for a 120 volt socket is a resistor of sorts. If you held the bottom center contact to 120 volts the outside of the threaded part of the base of the bulb would read 120 volts.

This post was edited by used red MN on 01/28/2023 at 12:23 pm.
 
JL, iffffffff you have an actual electronic VOLTAGE REDUCER that converts 12 volts down to 6 that has adequate power rating, NOT just a resistor (would need to know actual current to drop 12 to 6) that should suffice to serve as a substitute to replace the 6 volt battery to power up the IGNITION ONLY......I dont like the idea of bypassing the ignition resistor as it could shorten points life ???

Those 6 volt pony motors (iffffffff in good shape) werent hard to start even in cold weather and even at 6 volts their starter motors cranked plenty fast enough. While sure short term 12 volts on a 6 volt starter shouldnt damage it, but its NOT the same as 12 volts on 6 volt engine starter motors as the ponys cranked so easy IE its more risky (on the starters) to use 12 on a pony starter than 12 on a 6 volt engine starter motor, but it can work..NO WARRANTY ON STARTER

About the only main advantage of 12 volts on a 720 is maybe brighter lights, as the cranking and other accessories worked fine at 6 volts. Its a job to change genny and voltage regulator and gauges etc to 12 but hey thats up to YOU .......

Just be sure you have a true adequate power rated 6 volt reducer and use it for the ignition and change all else to 12 volt systems.

Theres NO voltage drop across an inline series resistor UNLESS THERES A CURRENT DRAW IE V = I x R

Id Blksmoke is here he is more current and sharper on pony starters and systems than myself but I believe the above is still true.

John T Rusty on 720 Ponys its been too many years grrrrrrrrrr
 
I'll try to attach a photo of what I got. It was labeled as a 12v to 6v voltage reducer. It's slightly bigger than the original ceramic resistor. Hopefully it's the right thing. I'm a roofer by trade, I'm just winging it here, ha!

I have fun at local pulls with this tractor. It's tweaked a bit and I'm using a 12v electric fuel pump now. I did just have a sperate little 12v motorcycle battery to power the pump but i was always weary of running that down too low. Thought this winter id simplify things and just make the whole tractor 12v if i can. I don't really care for the electric start conversions and my pony runs good, thought I'd keep it.

Thanks for the help gentleman.
cvphoto146128.jpg
 
I searched and found what I think is the component he has. Here is where more electrical knowledge than I have will prove beneficial. If I read it right I believe it is a 1 ohm resistor, see photo.

cvphoto146156.png
 
That looks right. I didn't notice any writing on the one I have but I'll check again. I just searched 12v to 6v voltage reducer on Amazon and that's what came up along with some ceramic looking resistors like I already had.
 
Best I can tell from the photo thats only a 1 ohm power resistor NOT any electronic 12 to 6 Voltage Regulator

HOWEVER if its resistance were near the same ????????????????????? as what the normal ignition system is and formed a 50 50 voltage divider (for a 12 volt battery) that dropped 6 volts and left 6 for the ignition IT CAN WORK

That being said if its 1 ohm and drops 6 volts the normal factory ignition would be 1 ohm WHICH I DONT HAVE FACTORY SPECS FOR but doubt its exactly 1 ohm BUT HEY IF IT WORKS AND DROPS 6 VOLTS LEAVING 6 SAME AS THE ORIGINAL 6 VOLT BATTERY it will work

With all in place wired up and ignition on so its drawing current check the voltage on its output to ignition and if its in the 5 to 7 volt range that should be okay BUT NO WARRANTY THIS ISNT MY IDEA OR PREFERENCE LOL

John T
 
One last thought....Ifffffffffffff the factory original WICO Distributor Ignition operates at 4 volts due to an ignition resistor dropping 6 down to 4 that feeds the WICO (No factory specs here not sure) and you want to do away with the factory ballast JUST BUY A 12 TO 4 VOLT ELECRONIC VOLTAGE REGULATOR and use it to feed the WICO ignition.....Just saying in theory I dont have specs or data here NO WARRANTY

Theres still all the charging and accessories and gauges to deal with in converting 6 to 12 and hope 12 volts on the 6 volt pony starter works with no harm

John T
 
Thanks for the help. I'll see what it shows on my meter.

I'll add, I hold you nor anyone else responsible if I let all the smoke out of the wires. Hahaha!
 

Can only find a 3amp version but there must be higher current versions out there .

https://www.amazon.ca/DROK-Waterproof-Converter-Adjustable-Transformer/dp/B00C0KL1OM/ref=asc_df_B00C0KL1OM/?tag=googlemobshop-20&linkCode=df0&hvadid=292951377574&hvpos=&hvnetw=g&hvrand=4900390320380676979&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9047930&hvtargid=pla-570676551581&psc=1
 
EXACTLY and since its a ONE Ohm resistor and V = I x R/1, the voltage drop across the 1 Ohm resistor is
the same as the current.

If the ignition circuit draws 8 amps the resistor drops 8 volts leaving 4
If the ignition circuit draws 4 amps the resistor drops 4 volts leaving 8

Hey that one ohm resistor may (depending on current) drop enough voltage so the initial 12 battery volts
gets reduced enough so the WICO distributor will function fine and MAYBE NOT ?????? over current or over
heat the points or coils ????????

Bottom line sure it can WORK but my preference would be a 6 Volt electronic voltage regulator to replace
a 6 volt battery BUT ITS THE TRACTOR OWNERS CHOICE

John T
 

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