420 running issues, spark, battery, points?

gohammergo · Post by **gohammergo** » Sat Feb 01, 2014 4:39 pm

Hi All,
I think this may be my first post here ever! Have a question about my 420.
First though, some history on it. My dad bought this used 25+ years ago and rebuilt the engine on it. He used it off and on for a few years, probably less than 100 hours on it. In the last 15 years that he was alive, it ran maybe twice, and both times for just short durations. Always fired right up though. So, when I inherited it and tried to start it, it would not go. Turned out that it needed points. So, I put pints in it and used it maybe 30-40 hours. Started and ran great every time. Then, about two months ago, I was going to use it to clean out the horse pen and it started misfiring, backfiring and wanting to die out. Seems like it started when I would go over a bump or when the machine was jarred. Then it died out completely and would not start at all. I thought at the time that it seemed like there was something in the gas tank or the carb bowl that would disrupt the fuel flow when the machine was jarred. So, I took the carb off and cleaned it but still wouldn't start. I then checked the points and there was no spark, so I put in new points. Fired up and ran fantastic.

I used it to plow snow a couple of times, maybe ran for 10 hours or so tops, and it is acting up again. Runs just like it did the last time it needed points. Now, I am running an 8 volt battery in it and when I researched into charging the 8 volt, there was a lot of talk that an 8 volt battery will chew up points. I did smooth the points with 400 grit fine sandpaper, but it still didn't run the way it should.

I'm going to pick up some points tomorrow and see if that will fix it again. So, does the higher voltage battery burn out points? Whet are the carb adjustments supposed to be?

Thanks in advance, John

Stan Disbrow · Post by **Stan Disbrow** » Sat Feb 01, 2014 5:18 pm

Hi,

One thing to check is the points you put in are for a positive ground system and not negative ground. The point materials are swapped between the two types. If they are reversed, they will pit badly in a hurry.

Stan

gohammergo · Post by **gohammergo** » Sat Feb 01, 2014 6:22 pm

I didn't know there was such a thing in the points. I asked at the supply for points for the 420, I assumed they were the proper ones.

When i looked at the points tonight, they were showing roughness. I sanded them down with 400 grit body shop sand paper and then worked a dollar bill between them to clean.

Speaking of that, has anyone heard about using paper money to clean points after filing? My dad always did that. I think he said there was some kind of chemical in the paper money that helped keep coins clean when they were in your pocket together. It's probably just some kind of old tale, but I never have researched it either.

So, one of our auto supplies are open tomorrow. I'll call and ask about it.

Thanks for taking the time to answer Stan.

Best wishes, John

DukeofDeere · Post by **DukeofDeere** » Sat Feb 01, 2014 7:14 pm

The coil is probably getting cooked from the 8 volt battery.
6 volts a good starter and good cables are all that is needed.
Never replaced points in 22yrs and 1200+ hrs of use all seasons.
Can even start it with the hand crank with fresh gas.

Duke

Gil · Post by **Gil** » Sat Feb 01, 2014 7:32 pm

Dollar bills are made out of extremely high quality linen paper. It leaves no lint and will not tear easily.

Make sure your distributor is free of moisture. Remove the points plate and clean underneath it. Also look closely at the insulator around the wire coming into the distributor. Look at all the wires and terminals in the entire ignition run from the spark plugs, to the distributor, to the coil, and on to the ignition switch. Gil

Post by **Lavoy** » Sat Feb 01, 2014 8:52 pm

Go back to 6 volt battery, check the polarity of the coil to ensure it is wired correctly just in case, not a big deal, but does adversely affect the spark to a degree.
Lavoy

gohammergo · Post by **gohammergo** » Sat Feb 01, 2014 9:37 pm

Well, looks like I need to be shopping for a new battery then. I have another good coil off my parts machine and I'll get a new set of points as well.

So, another question about the battery. The battery is only a year old, and the battery in my Ford 8N is shot... I think the Ford has a magneto system. Will the 8 volt work ok in that?

Again, thanks to all who took the time to answer.

John

Post by **Lavoy** » Sat Feb 01, 2014 11:35 pm

Much better in terms of the ignition, they are still worthless in my book as far as starting.
Lavoy

Stan Disbrow · Post by **Stan Disbrow** » Sun Feb 02, 2014 6:24 am

Hi,

The 8v battery does not offer enough extra energy to bother the coil or the points. And, the 6v generator can't raise the battery voltage above 8v in the best of condition. So, you are OK there. BTW, an 8v battery should be 9.5v under charge to prevent sulfation of the plates. So, an 8v battery will not last as long in a 6v system as a 6v one will.

As far as starting goes, multiply the CCA rating of batteries by the voltage. That figure is the power available to the starter. Some 6v batteries have less power than an 8v, some more, so it is not automatic that an 8v gives more power than a 6v.....

Stan

Gil · Post by **Gil** » Sun Feb 02, 2014 6:59 am

Twinkle twinkle little star,
power equals I squared R.

......or equivalently, as Stan says IV.

Stan Disbrow · Post by **Stan Disbrow** » Sun Feb 02, 2014 9:45 am

Hi,

Yup. Traditionally, current is I and voltage is E, and power is P, so the magic formula is...

PIE!

Mmmmm. Pie!

I squared R gets you the power loss, like when you use a skinny 12v wire between the battery and the starter on a 6v system.

Stan

gohammergo · Post by **gohammergo** » Sun Feb 02, 2014 11:55 am

So, I guess now I am getting confused about this. Does the 8 volts raise havoc with the ignition or not? If it does, and that's why the points went bad so soon, then that gives me a valid reason to go to a new 6 volt battery. I got a pretty good deal on the 8 volt battery and it's only about a year old. The guy I got it from said that he runs 8 volts in all of his 6 volt equipment and had no troubles with it, which is why I decided to buy it. If the 8 volts is no issue, any idea why the points would go bad so quickly? My dad and I logged for several years with our 430 Deere and I remember him changing points in that only one time. The machine does spin over a lot faster with the 8 volt than it did with the six volt.

jtrichard · Post by **jtrichard** » Sun Feb 02, 2014 12:13 pm

yes the 8v should NOT be a problem i have seen 12v on a 6v coil that lasted much longer that yours is but it fries the points .... have you checked the voltage when it is charging/running? you could try a dropping resistor on the coil and see what happens ... if it will start and run with the resistor i would run it and see how long they last then

OK i know yours is 6/8 volt but take a look at this (its for 12v) http://www.atomic4.com/balres.html and it may give you some info on what you might do

Stan could most likely tell you what the ohm value of the resistor might be that you could use... one thing i do know about electricity is if you stick your finger in a light socket that is turned on it HERTZ

if no one else gets it Stan will LOL

Stan Disbrow · Post by **Stan Disbrow** » Sun Feb 02, 2014 12:59 pm

Hi,

The 6v generator and voltage regulator will just barely let the 8v battery hit 8v with only ignition load. And that is only 1/2 volt higher than the 7.5v you get with a 6v battery in place.

So, no. Nothing to hurt points with having a 8v battery in place. Farmall at one point went to 8v on their 6v machines and those use the same points as their 6v counterparts did.

It is far more likely you are seeing electromigration of the point contact material from having negative ground points in a positive ground system. I know that NAPA has two part numbers for the old 6v machines because of conversion of the ground when switching from 6v to 12v.

The value for the voltage drop resistor when switching to a 12v battery is 120 ohms, 10 watts. So that will be a ceramic cased wire wound resistor. If you wanted one for 8 volts it would need to be around 40 ohms, but no one bothers unless also changing the generator and regulator to allow the 9.5 volt full charge level. I would not bother.

There was a year or two when I was running an 8v battery in my 420c when it seemed no one had a 6v on hand. All I did was stick it in. They do not last time-wise like the 6v ones do. The low full charge voltage leads to a higher than normal sulfation of the battery plates. Once the 8v battery crapped out, I returned to a 6v one, and a new set of cables.

That last is the secret to a 6v system. The least little oxidation or corrosion anywhere in the main power leads, and there is too much of that I2R going on.

And, yes. Good one there. Sticking any body parts across 120 VAC does Hertz!

Henrich Hertz was an electrical pioneer, and AC Cycles Per Second is known by his last name (Like Volta, Ampere, Ohm and Seimens are electrical pressure, flow rate, resistance and conductance).

Stan

Howard Yoder · Post by **Howard Yoder** » Sun Feb 02, 2014 4:18 pm

Get a new condensor with the points that can cause the problem you described

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420 running issues, spark, battery, points?

420 running issues, spark, battery, points?

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