420 running issues, spark, battery, points?

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Lavoy
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Post by Lavoy » Tue Feb 04, 2014 6:39 pm

That would make sense too.
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gohammergo
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Post by gohammergo » Sun Feb 09, 2014 11:55 am

Lavoy, I will get back to you when we get a break in the weather. Sorry for the delay in responding. Usually when there was any action on this thread, I would get an email about it. Haven't gotten one and figured that it had kind of faded out!

This machine has always been 6volts. We bought it from the original owner and all he ever did was run it. If it had been converted to 12v, I'm sure my father would have been aware of it.

I'm going to check the bushings on the distributor today and see if there is any play in it.

Thanks again to all who read and answer.

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Post by gohammergo » Sun Feb 09, 2014 2:33 pm

On second thought. I think you have my email in your files. If you want to send me an invoice for the parts I can pay either via paypal or other credit card. Than I will have them for when it does warm up.

Thanks again, John

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Post by Lavoy » Sun Feb 09, 2014 2:45 pm

John,
My e-mail is at the bottom of any of my posts, send me a message when you are ready to go, and I can get parts coming your way.
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Ray III
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Post by Ray III » Wed Feb 12, 2014 12:08 pm

You say the ignition cuts out when you go over a bump. That sounds like an ignition wire broken inside the insulation. After 50 years of being jostled around, heated and cooled, etc. wires will eventually fatigue and fall apart. It's very likely that when you replaced the points again, you moved the wires around and restored the connection. An 8 volt battery would also appear to work better because it's more easily able to push current past those bad spots.

This can usually be checked by rattling the wires around as the engine runs, if there is any hint of a skip then the wire harness is junk.

If you want to keep the 8 volt battery you need to adjust the mechanical regulator behind the ignition switch to the appropriate charging voltage. However, there is absolutely nothing wrong with the 6 volt system, as long as you have the correct heavy gauge cables, charging system in good working order, and a good battery (John Deere). Also make sure you have fresh ISO 32 oil in the hydraulic system as waterlogged or heavy oil will make for hard cold cranking.

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Post by gohammergo » Fri Feb 14, 2014 10:19 am

I'm going to check out the wiring today, but I think I know what the problem is, and I think it was mentioned already here too. I spoke with a different parts guy this morning and asked about the positive ground points. He said he had never heard of them, and when I explained what was happening, he said it sounded like the resistor on the switch was bad. That's when the light went on! One of the last times my dad went to use this machine it wouldn't start, so he and a buddy ran a jumper wire from the coil to the battery. This was done very spur of the moment and to start the machine you had to twist two wires together. When I inherited it, I put a toggle switch in it. So, what I have to do is figure out why they ran the jumper wire and fix it. I do have another known good switch, and when warm weather gets here or my ambition level rises I'll change out the switch.

This brings to mind another question. It seems to me that the switch has several different positions on it. I assume one is for running, one for running with the lights on? The rest?

Thanks again for all who take the time to answer these questions!

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Post by Lavoy » Fri Feb 14, 2014 10:30 am

The resistor on the switch is not for ignition, and will have no effect on it. The resistor is for dim headlight setting, nothing else. Doesn't mean you still don't have a wiring problem, but your parts guy is all wet if he thinks it has anything to do with the resistor. There is no resistor used on any 6 volt ignition system that I have ever encountered, only 12 volt.
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Tigerhaze
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Post by Tigerhaze » Fri Feb 14, 2014 1:31 pm

gohammergo wrote: One of the last times my dad went to use this machine it wouldn't start, so he and a buddy ran a jumper wire from the coil to the battery. This was done very spur of the moment and to start the machine you had to twist two wires together.
Without looking at a wiring diagram, I would assume that the coil wire is run through the ignition switch, and when the wiring failed your dad bypassed the bad section of wiring by jumping it directly from the battery. As I previously mentioned, I would check the ignition switch and associated wiring for continuity as it has probably disintegrated internally as Ray suggested.
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Post by original possum » Fri Feb 14, 2014 4:25 pm

I beg to differ with anyone, but my 40C has two wires to the coil. One comes from the oil pressure switch mounted under the generator and the wire going TO that switch disappears into the dash panel. The other wire goes from the battery to the dash panel and then directly to the coil. I'm not going to pull the dash panel to look, but did years ago. At that time, I found a resistor that was in service when the starter was not pulled, but when the starter was released the current flowed thru the other wire. The purpose was to give the spark more oomph when starting but reduce the current across the points when running (otherwise why have the oil pressure switch?). At that time I bypassed the lower flow setup and went from the starter to the switch to the coil, leaving a connector to stop this flow after starting, if I want, or leave it connected to get a hotter spark. I don't run it enough that point life is an issue. BOTH paths are on the same switch terminal, so it still kills by switch.
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Post by Lavoy » Fri Feb 14, 2014 4:47 pm

While yours may have two wires to the coil, it is definitely not anything factory. There is also no provision on the factory starter switch for any sort of bypass to full voltage, nor is one necessary on 6 volt ignition systems.
The wire from the pressure switch would go to the hour meter if so equipped. If not so equipped, then again it is some sort of field modification, and has nothing to do with the factory wiring, and is in all likelihood a sort of "Murphy" switch to kill the engine if there is low oil pressure.
It appears we may be kind of having two different discussions here, what a given crawler has on it now 50 years later, and what it left the factory with. I am speaking only to what they were manufactured with, and I can quite confidently state that there is no form of resistor or any other sort of contrivance between the ignition switch and the coil. The wire goes from the IGN terminal on the switch directly to the negative terminal on the coil in one continuous unbroken string. Any variance from this is not factory, and has been added by a previous owner.
I tried to upload the wiring diagram, but can't get it to load, but anyway, it is the blue wire if that helps.
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Stan Disbrow
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Post by Stan Disbrow » Fri Feb 14, 2014 5:04 pm

Hi,

The contact points were made with a Silver contact on the Negative side, and a Copper/Silver alloy on the positive side. This reduces electromigration between the contacts.

If the polarity is reversed, then electromigration is accelerated. It has to do with electron flow between metals higher and lower on the atomic scale. So, there used to be Positive Ground and Negative Ground point part numbers.

Since points are all but gone in this world, any you find brand new (as opposed to NOS) are likely to be Negative Ground points.

Just another thing to make one switch over to 12v negative ground..... And a CDI unit. I have a couple left over from racing. Might make a 420 hot rod! How about a velocity stack on the carb to boot! :P

Stan
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Useta Have: '58 JD 420c 5-roller w/62 inside blade
Useta Have: '78 JD350C w/6310 outside blade
Useta Have: '68 JD350, '51 Terratrac GT-25
Have: 1950 M, 2005 x495, 2008 5103 (now known as 5045D)

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Stan Disbrow
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Post by Stan Disbrow » Fri Feb 14, 2014 5:23 pm

Hi,

Ok. No 6v system had a resistor between battery and coil. None. Ever. The coil.*is* 6v.

Early 12v systems had a 6v coil. So to not fry the coil, they used a resistor between the battery and the coil.

To ensure that 6v went to the 6v coil when the 12v battery was under starter load, they had a bypass in the starter switch to jump across the resistor. That switch might be part of the ignition switch, or a terminal on the starter solenoid.

There are 12v coils in the world. Do not use a resistor in the line with them. They will start fine, but quit as soon as the key is in the run position. ;)

Your 420 has a resistor on the ILBD switch. It is *not* Ignition related. It is Dim lights related. Jump it and it will not fix the problem.

You might have a flaky I position on the ILBD switch. I do on my 420. I installed a toggle switch with a new pair of wires between the battery and the coil. That is now my ignition switch. I flip that on and leave the ILBD switch off, unless I want lights.

Why did I do it that way? I am too lazy to actually replace the ILBD switch!

What is ILBD?

Ignition
Lights - Front only
Bright rear light
Dim rear light

Oh, and mine has no resistor on the ILBD switch. Mine has two bulbs in the rear light housing. Bright is the sealed beam. Dim is a tail light bulb that shines through a ruby red filter in the reflector silver of the sealed beam.

It took me a while to understand what y'all were talking about, a resistor on the switch....

Stan[/list]
There's No Such Thing As A Cheap Crawler!

Useta Have: '58 JD 420c 5-roller w/62 inside blade
Useta Have: '78 JD350C w/6310 outside blade
Useta Have: '68 JD350, '51 Terratrac GT-25
Have: 1950 M, 2005 x495, 2008 5103 (now known as 5045D)

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Stan Disbrow
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Post by Stan Disbrow » Sat Feb 15, 2014 5:19 am

Hi,

Last night, I got to poking around some old car chat boards, and there was some chatter about issues with new points in old cars. It seems a lot of newly made points are using sliver plated copper for the contacts and those need dressing a lot more frequently. Perhaps this is what has been happening here. I can easily see where silver plate would wear off leaving just copper for the face.....

Stan
There's No Such Thing As A Cheap Crawler!

Useta Have: '58 JD 420c 5-roller w/62 inside blade
Useta Have: '78 JD350C w/6310 outside blade
Useta Have: '68 JD350, '51 Terratrac GT-25
Have: 1950 M, 2005 x495, 2008 5103 (now known as 5045D)

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gregjo1948
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Post by gregjo1948 » Sat Feb 15, 2014 6:45 am

Hey Stan--If you're adding a velocity stack, you might as well install racing slicks! :lol: gregjo1948
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DrLoch
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Post by DrLoch » Sat Feb 15, 2014 7:57 am

If the 6 volt ignition/points appear to be the issue, convert it to electronic. Pertronix offer units for 6 volt with positive and negative ground. The 6 volt tractor guys have been using them with good success. Or as Stan suggested convert to 12 Volt and use one of his old CDI units :D As long as the wiring is good that will light a fire. If you really want to get tricky convert to 12 volt and coil on plug, you'll be the talk of the town.
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