I have a 560 gas - it has electronic ignition, but the original set up on the coil with ballast resistor.

It's my understanding that it starts using 12 volts through the coil, but run at 6 volts - do help save the points.

With the electronic ignition - I'm guessing there's no need for this:

What do other people do here? I've been googling, but it's confusing me.

Can I just use any 12 volt coil in place of the old one, and bypass the resistor completely? Am I overthinking this?

I have my reason for wanting to change the coil anyways - but I'm just not sure what to do.

Quoting Removed, click Modern View to see

rvirgil, on the contrary, here's what the official pertronix instructions state, as copied from THEIR instructions:



Dunno WHY no one looks at the actual mfg's instructions for these things????

JR, keep the starting bypass, it gives you the best of both worlds, makes up for low battery voltage caused by the load of the starter during cranking, yet inserts the ballast resistor in the circuit as soon as the starter is disengaged to ovoid overloading the module and overheating the coil.

Yo Bob, yep amazing what manufacturers instructions can do for ya lol. Some don't realize that while cranking a 12 volt battery drops voltage and subject to temperature and engine condition and battery and oil viscosity and cable voltage drop etc etc etc it may drop to 9 or 10 volts (IE coil current isn't temporarily DOUBLED) so the ballast by pass system (its ONLY while cranking) can improve cold weather starting.

John T

I would use the 3 ohm coil as Pertronix recommends. Will save you a lot of confusion. Make sure you get a coil marked "12 volt no external resistor required" not on labeled "12 volt - use with external resistor"

You can not use the cold start bypass with Pertronix. The bypass which applies 12 volts to 6 volt coil doubles the voltage at the coil thus doubling the current through the coil and the electronic switch. Electronic devices are not as forgiving of out of design tolerance voltage and current as mechanical points would be.

If using the bypass and doubling current through the Pertronix, I would expect premature if not immediate failure of the device.

JR, all good questions I will address them one at a time.

1) "It's my understanding that it starts using 12 volts through the coil, but run at 6 volts - do help save the points."

With a 12 volt tractor using a 6 volt coil plus external ballast resistor, that's primarily to improve cold weather starting as full unballasted voltage is on the 6 volt coil ONLY while cranking (cuz ballast is bypassed), afterwhich its 6 volts on a 6 volt rated coil as the ballast drops approximately 6 volts. Its NOT so much to save points, although sure if 12 volts were constantly applied to a 6 volt coil the points would burn up prematurtely...........THE SYSTEM IS MOSTLY TO IMPROVE COLD WEATHER STARTING.............

2) With the electronic ignition - I'm guessing there's no need for this:

NOT necessarily so. The elec switch simply replaces the mechanical points switching, the rest is still the same. Even if points or an elec switch is used the 6/12 system still improves cold weather starting, although sure, the tractor still runs fine if you toss the ballast and use a full true 12 volt coil, regardless if points or an elec switch is used.

3) What do other people do here? I've been googling, but it's confusing me.

SOME toss the ballast and use a new full true 12 volt coil SOME retain the old 6 volt coil and ballast bypass system which can improve cold weather starting SOME use an after market so called high energy or high voltage 12 volt coil provided the elec switch can handle its current

4) Can I just use any 12 volt coil in place of the old one, and bypass the resistor completely? Am I overthinking this?

YES you can toss the ballast and bypass system and use a new full true 12 volt rated coil.

5) I have my reason for wanting to change the coil anyways - but I'm just not sure what to do.

THATS YOUR CHOICE NOT OURS If you want to change the coil anyway GO FOR IT.

REGARDLESS if points or elec switch is used you can still EITHER use a 6 volt coil plus ballast and bypass orrrrrrrrrrrr a new full true 12 volt rated coil of your choice which the elec switch can handle.

Others may add to this, I'm sure I forgot something. There are advantages and disadvantages either way but I'm NOT going into all that, just trying to answer your questions

John T

actually I downloaded the instruction sheet from pertronix - they say it must be a coil with a minimum of 3 ohms resistance in the primary coil (for a six cylinder system) Otherwise you need a ballast resistor to reach the required resistance.

So - now I'm even more confused.

Are they assuming the use of a ballast resistor in a different way than the 560 uses it? If I were to simply replace the 6volt coil with a 12 volt, and keep the ballast resistor - ... wouldn't the coil only be getting 6 volts when running? And one would assume, not work?

It sounds like if I went to a 12 volt coil - that has less than 3oms internal resistance - that I'd still need a ballast resistor, but with it wired differently than it is now. Yes?

LETS TAKE YOUR QUESTIONS ONE AT A TIME

1) Tactually I downloaded the instruction sheet from pertronix - they say it must be a coil with a minimum of 3 ohms resistance in the primary coil (for a six cylinder system) Otherwise you need a ballast resistor to reach the required resistance.

SURE that makes sense. The elec switch is only rated to switch x amps, so if Pertronix is telling you they need a minimum of 3 ohms coil SIMPLY BELIEVE THEM AND DO AS THEY SAY otherwise you may over current and damage the elec switch...... NO NEED FOR CONFUSION the combination of the coil PLUS any external ballast needs to be at least 3 ohms JUST DO IT !!! A typical 6 volt coil may only have like 1.5 ohms so you need a 1.5 ohms at least ballast so there's 3 ohms TOTAL which may be near original configuration soooooooooooo if you keep the old 6 volt coil you should ALSO keep the old ballast (still need 3 ohms total) BUTTTTTTTTTT if you use a new full true 12 volt rated coil it should have at least 3 ohms resistance (which is typical) in which case you don't use any ballast GET IT ????????????

2) So - now I'm even more confused. NO NEED, READ THE ABOVE

3) Are they assuming the use of a ballast resistor in a different way than the 560 uses it? If I were to simply replace the 6volt coil with a 12 volt, and keep the ballast resistor - ... wouldn't the coil only be getting 6 volts when running? And one would assume, not work?

Read the above again....... If you use a new full true 12 volt coil (at least 3 ohms) DO NOT USE THE BALLAST 4) It sounds like if I went to a 12 volt coil - that has less than 3oms internal resistance - that I'd still need a ballast resistor, but with it wired differently than it is now. Yes?

YES if the new coil is less then 3 ohms you need additional series ballast so the TOTAL is at least 3 ohms BUT many full true 12 volts coils are already near 3 ohms

NOTE of CAUTION some high energy high voltage after market coils may be less then 3 ohms so do as Pertronix says YOU NEED AT LEAST 3 OHMS

The 6/12 system with a ballast bypass improves cold weather starting and so long as you still have 3 ohms total (6 volt coil PLUS ballast) you can sue the Pertronix switch

Ifffffff you insist on a new 12 volt coil so long as it has 3 ohms (which most do) you can toss the ballast and all is still well

John T

yes that makes sense, and I ended up ordering the flamethrower coil (3 ohm) for simplicity.

The reason I was considering a 12 volt coil with less than 3 ohms is that's all that's available in the car part stores around me (as in "in stock"), I'm getting this tractor ready for the memorial day parade, so I'm in a pinch and needed it by today.

The tractor doesn't run well, kinda skips and stumbles a lot. I've rebuilt the carb, timed it, adjusted valves, put new plugs in, new wires, checked the compression, using high octane gas, even cleaned out the gas tank and lines - lots of nasty rust in there, cleaned out the carb again - All to no effect.

I'm still very suspicious of the carb, but I figured for 20 or 30 bucks, might as well swap the coil out for peace of mind. But I'm thinking it's not likely to fix my problem anyways, so really not a big deal. Either way- that's what got me wondering about the ballast resistor. I undestand it more now.

So thank you for your help.