656 Electronic Ignition

Hey guys! So the 656 I'm working on has been converted to electronic ignition (pertronix ignitor). This was done shortly after the owner noticed it was running poorly and lacking power. Now I have found some mechanical issues, but had a few electrical questions as well.

First, coil says external resistor required, but I don't see one. Is it not needed with the 12v electronic ignition? It is not Pertronix's flamethrower coil they recommend.

Secondly, tractor has copper core plug wires but I see online that carbon core wires are recommended with the electronic ignitions. Should I change them and why?

Lastly, it has Autolite 3116 non-resistor plugs in it. I would typically install 386's but am wondering if it matters as much with distributor ignition as it does with magnetos.

Basically I don't want to go spending someone else's money on unnecessary changes, but will go ahead with them if its going to make tractor run better.

Thanks for the help!!

Say Kid, the Farmall doctor in the red Power magazine just had a very informative article on that very subject, i hope u get the publication, It's very informative.

Just for fun change back with stock set-up and see what happens those things can be trouble.

Pertronix is fine, I recently had to change one that went bad, Pertronix stood behind it no question about it. The fellow at pertronix asked me if I was running solid metal wires or carbon I told him solid--he said you need to change those because it has been a problem with some old solid wires that have cracks in them causing issue with the electronic module.
I have been running these things for a long while, had one on my 240 for over 21 years and never an issue. But you need to get a coil that does not require an external resistor, you do not need the pertronix coil I get mine from Napa can not remember the number maybe UC-15 but do not rely on that.

I have run both 3116 and 386 and see no difference, now I run NGK AB6 just because the heads are 13/16 making it a little easier in some tight spots.

Resistor--
Not to say this is the case, but sometimes a resistive wire is used instead of a Resistor.
The easiest way to check for a resistor in the circuit is to ground the "-" terminal of the coil, turn the ignition switch ON and check the voltage at the "+" terminal of the coil. If you get 12 volts, then there is no resistor.
The resistor doesn't have to be at the coil, it may be under the dash panel or somewhere else.

Ballast resistor is located above the voltage reg. behind the right instrument pannel cluster. From a post on this site from 2006

Definitely verify that there's no resistor, and if there isn't one, put one on. Running without a resistor, your coil has an expected lifespan of about 20 minutes before it overheats.

Like others have said, the resistor may be well-hidden.

There should also be a second wire running from the starter solenoid (a post labeled "S") to the coil with NO resistor on it, if I'm not mistaken. This is to boost voltage to the coil while cranking the engine over.

You may find the tractor hard to start if you put a "no resistor required" type 12V coil on it.

(quoted from post at 05:01:43 03/23/17) Definitely verify that there's no resistor, and if there isn't one, put one on. Running without a resistor, your coil has an expected lifespan of about 20 minutes before it overheats.

Like others have said, the resistor may be well-hidden.

There should also be a second wire running from the starter solenoid (a post labeled "S") to the coil with NO resistor on it, if I'm not mistaken. This is to boost voltage to the coil while cranking the engine over.

You may find the tractor hard to start if you put a "no resistor required" type 12V coil on it.

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I have a 1940 M, converted to 12 volts. I have one of those "no external resistor required" 12 volt ignition coils on it. The engine always starts immediately. No hesitation at all.

I saw that on the online parts manual. Will have to look tonight and see if there is one hidden up there.

I have a 1940 M, converted to 12 volts. I have one of those "no external resistor required" 12 volt ignition coils on it. The engine always starts immediately. No hesitation at all.

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Apples and oranges, first of all. You're talking about a low compression 4-cylinder engine vs. a high compression 6 cylinder engine. The M cranking doesn't draw down the battery as much as the 656 will.

You can do whatever you want, but I'm just stating how the tractor was set up originally, so that if you do have problems, you'll know why.

(quoted from post at 10:16:54 03/23/17)

I have a 1940 M, converted to 12 volts. I have one of those "no external resistor required" 12 volt ignition coils on it. The engine always starts immediately. No hesitation at all.

Click to expand...

Apples and oranges, first of all. You're talking about a low compression 4-cylinder engine vs. a high compression 6 cylinder engine. The M cranking doesn't draw down the battery as much as the 656 will.

You can do whatever you want, but I'm just stating how the tractor was set up originally, so that if you do have problems, you'll know why.

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But the high compression, 6 cylinder 656 also has a larger battery and a more powerful starter.

To clarify what K-Mo is suggesting, to do the check for 12V or if it has a resistor the points must be closed.