Burned Points

[Ron Petterson]

For a number of years I have had issues with an 8N with front mount distributor burning points. Original 6v system, not 12v conversion. I have been told bad points, so I bought NAPA, New Holland and Blue Streak. Same issue with all. Was told that it was bad bushings in distributor, but there is no identifiable change in point settings if the shaft is moved after resetting gap. So I contacted Jeff in the parts about a new distributor and he said it sounded like it could be bad resistor allowing to high a current to distributor. With that, I used an ohm meter on the resistor and this was the result I shared with jeff. And he said share it on the forum for input.
Here is what I'm getting.
My meter settings are at 2m, 200k, 20k, 2 and 200 settings
Was not able to get a reading on the meter for the first three settings.
At 2 the reading was .002
At 200 the reading jumped to 4.0 then dropped to 2.0, fluctuating between that and 2.4
The switch was off on the tractor. Wires were not removed from resistor.
The measurement was between the two post in line, not the third one making a triangle.
And finally, my ohm meter gives a reading of .2 at the 200 setting when leads touched to themselves.
So my questions.
Did I measure the resistance correctly or do I need to do something different?
Was the reading on the resistance OK.
If these reading are OK, then I am going to buy the replacement distributor so I don't have to remove, clean and reset points after a couple hours running. It runs fine as long as it has started, but once turned off, it will not refire.
I also have been removing battery cable to remove any power that might be leaking through the system when not running that might have been getting to the points. Not something that was likely, but did it anyway.
Thanks for any info you can share.
And I know little to nothing about electronics . So I ask any info you provide to be kept simple so I can understand. Yes I am dumb when it comes to electronics.
I would have had a mechinic who knows these tractors come and check this for me, but they are far a few between in this area and hard to find

 

[Bruce (VA)]

It is unlikely that a faulty OEM ballast resistor is causing burnt points. Possible, but unlikely.

First, do you know the difference between the oem ballast resistor and the ceramic resistor? I ask because that might be your problem.

Testing low resistance is difficult w/ a cheap meter.

But, you are doing it correctly, first by determining the resistance in your test leads. Subtract that from the reading you get.

The oem ballast resistor should read .3 ohms cold and 1.7 ohms red hot. Just worry about the cold reading.

You might want to consider other more likely causes of burned points.

Usually burned points will have pits on one side & raised areas on the others. Sometimes they just wear unevenly. They will most always discolor as they have a coating on the surface. The usual causes of burned points are absence of cam/wearing block lubricant, condenser failure, a decreasing gap caused by wear on the rubbing block, mis-alignment, sanding w/ a point file, excessive current, setting an incorrect gap, leaving the ignition key on w/ the points closed, use of incorrect cam lubricant & poor quality metal. I've heard of points being welded shut, but I've never seen it happen.


My last set of points in my 1950 frontmount lasted 1 month short of 4 years, and that is by no means a record. I've got 3 N's, all 6v & all w/ points. I've never had a reason to convert any to 12v or install EI.

You can change points everyday & it will not fix bad bushings. If you are having trouble w/ points failure, check the shaft. If you detect movement, chances are it needs new bushings.

Just because I?ve never experienced a worn out distributor cam doesn?t mean it can?t happen.
Specs for the frontmount are:

Across flats = .789/.791
Over lobes = .869/.871 dia.

Sidemount measurements are:

Across flats = .72
Over lobes = .78 dia.

The next trick to points lasting a long, long time is annual maintenance. (tip # 40) No matter how well it's running, pull the distributor (or cap for a sidemount), check the gap & put a dab of points lube on the cam. Not bearing grease or Vaseline; use the correct lube.

Quality parts are critical to longevity. Having learned the hard way, I most always use Blue Streak brand points. They are made by Standard parts & available at many auto parts stores. (frontmount points also fit a 48 Ford as I recall) Beware of sticker shock: $16-18 a set. My next choices are Wells or Echlin. Look for a brown rubbing block. Unfortunately, many folks have experienced problems w/ points made by Tisco, Sparex, A&I Products and any TSC ignition parts..

Correct points installation & gap is also important. Make sure the blade is at a perfect right angle to the points & you want to feel just the slightest bit of drag when you pull the blade through the points. Make sure the blade is clean & that you dress the new points by running some card stock or a piece of brown paper bag through them. Gap is .015 on the frontmount, .025 on the sidemount on all four lobes of the cam. Make sure the points align correctly. Proper alignment is also critical to longevity. Look at the points when they are closed; both sides should mate evenly.

Even as tight as I am, I always change the condenser when I change the points??.and then I toss the condenser in the ?used? parts box. A bad condenser is rare; you can tell if the points are pitted/burned w/ metal transfer.

Good hold-down screws are important. (tip # 37) If the heads are wallowed out, what do you think the threads look like? You can use machine screws as temporary replacements, but you should use the OEM Fillister head screws. The larger head is there for a reason. If you do use standard machine screws, make sure they aren?t too long & interfere w/ the advance weights. Always use star washers under the screws.

Timing is important to engine performance. Make sure you set the point gap before you set the timing. Timing a sidemount is pretty straight forward; it has marks on the flywheel. It?s a bit different for a frontmount but it?s a necessary part of a tune-up nonetheless. And, contrary to what some folks think, timing a frontmount is not accomplished by getting #1 to TDC & putting the distributor back on the engine!

When I was 16 years old making $1.25 an hour & a set of points cost $1, I filed points. I must have been good at it because I recall it was almost a weekly exercise. If you ever file a set of points, you will remove the metallic coating on them & reduce the life span considerably. Unless you plan to keep on filing them, plan on replacing them pretty soon!

And lastly???it does not matter if it?s 6 volt or 12 volt, you must use the OEM ballast resistor on a frontmount. Too much current to the points will burn them up in short order (leave the key on with the points closed & you will experience this ?learning point? in about 3 minutes, tip # 38) For a 12v conversion on a frontmount, you probably need another resistor in the circuit as well but unless you measure the coil resistance, you will not know for sure. On a 12v sidemount, it will need a resistor if it?s a 6v coil (and even some 12v round coils need one) or you can just get a true 12v coil from NAPA & not worry about it. (tip # 30).
75 Tips

 

[Btzj02]

Even as tight as I am, I always change the condenser when I change the points??.and then I toss the condenser in the ?used? parts box. A bad condenser is rare; you can tell if the points are pitted/burned w/ metal transfer.

Drinking my morning coffee and had to chime in! A little trivia from the electrical transmission system. When operating an air switch on a high voltage system, if there is too much inductance, there will be a large arc and the switch may burn up when opened. To counter this inductance induced arc we place a capacitor in service which decreases the size of the arc when the switch is opened and prevents the switch from burning! Air Switch = Points, Inductance = Coil, Capacitor = Condenser. Like Bruce said: The Condenser is there to reduce the size of the arc across the points when opening and closing reducing the chance of pitting the points!

 

[Btzj02]

Even as tight as I am, I always change the condenser when I change the points??.and then I toss the condenser in the ?used? parts box. A bad condenser is rare; you can tell if the points are pitted/burned w/ metal transfer.

Drinking my morning coffee and had to chime in! A little trivia from the electrical transmission system. When operating an air switch on a high voltage system, if there is too much inductance, there will be a large arc and the switch may burn up when opened. To counter this inductance induced arc we place a capacitor in service which decreases the size of the arc when the switch is opened and prevents the switch from burning! Air Switch = Points, Inductance = Coil, Capacitor = Condenser. Like Bruce said: The Condenser is there to reduce the size of the arc across the points when opening and closing reducing the chance of pitting the points!

 

[R Geiger]

As far as I am concerned the ballast resister is there to protect the coil, not the points. If it was there to protect the points, then a side mount distributor would have a ballast resister also.

 

[Bruce (VA)]

yep.

It's there to reduce current to the coil, not the points. If points were voltage sensitive, you would see 6v & 12v points.
75 Tips

 

[Ron Petterson]

As far as I know, ceramic resistors have a ceramic core and wire outside, used more in electronics. Ballast resistors regulate voltage to reduce damage to coil.

Thats all I know about that.

Now, the meter I purchased was not the cheapest, but not the most expensive. mid range. So looking at the settings I provided. there is no way to get .3. I would either get .003 or 3.0. What I get is .002 or 2.0 when leads held to resistor for10-15 seconds

So I may not be able to measure the resistance with the one I have.

My points burn on one side leaving a residue on one side and pit on the other, Not much, but enough to cause them to fail.
So explain in more depth the cam wear lube. How does that reduce the burn over such a short time. I would think the points block would need to wear down before the burn would start under those conditions.

As for gap. I have that memorized. And the distributor has been off so often I can almost tell it to come off and it will by itself.

So since I am just as confused now as I was to begin with, I believe I will replace the cheapest parts to begin with once again (points and condenser), but adding the ballast along with points and condenser. Once that has been replaced and they still burn, seems like there will only be one thing left and that would be bad distributor. If that doesn't do it, then I am done trying to fix it.

Thanks for your response. As I said the only thing I know about electronics is a switch turns it on and off when it is working properly.

 

[Ron Petterson]

Hope you enjoyed your coffee! Thanks for the response. Going to replace points, condenser and the ballast since that is very inexpensive. If that doesn't do it, then the distributor next. If that doesn't do it, then I am finished. Nothing else left from my perspective.

have a wonderful day!
Ron

 

[Ron Petterson]

Thanks. Does make since to me since the juice goes through the coil first.
Ron

 

[Ron Petterson]

Bruce, Again thinks for your help!
Ron

 

[HFJ]

these tractors often use a ceramic resistor to augment the OEM ballast resistor in the case of a 12 volt conversion that is still using a 6 volt coil. in your 6 volt system, there is no reason for such an extra resistor, unless your goal is to prevent the tractor from starting, i suppose

it sounds to me like your resistor looks like this, correct?

 

[Ron Petterson]

(quoted from post at 20:49:09 02/22/20)
these tractors often use a ceramic resistor to augment the OEM ballast resistor in the case of a 12 volt conversion that is still using a 6 volt coil. in your 6 volt system, there is no reason for such an extra resistor, unless your goal is to prevent the tractor from starting, i suppose

it sounds to me like your resistor looks like this, correct?

H. That is what I have. Has not been coverted. When points are good, it cranks and starts fine. In cold weather, I might shoot a bit of starting fluid, but it has to be in the teens before I do that.
Thanks

 

[Bob]

It would be interesting to measure the primary CURRENT, points closed, engine not running, ignition switch "ON".

Conventional wisdom is that 3 Amps, or a bit more is good, and as you get up towards 4 Amps an higher it's rough on the breaker points.

Primary current can be measured accurately with less exotic test equipment than it takes to measure very low Ohms values accurately (ballast resistor).

 

[Ron Petterson]

Bob, thanks. So my limited knowledge tells me switch on creates current. Points closed completes circuit. Where do you recommend the best location for placing leads from amp meter to get best reading?

 

[Bob]

Since it is a series circuit, Amp reading will be the same throughout the complete circuit.

Do you have an accurate way of measuring DC Amps in the 5 Amp range?

 

[Bruce (VA)]

" that would be bad distributor."

Well, the only thing left to go bad would be the cam, bushings and advance weights. Have you checked them?

" My points burn on one side leaving a residue on one side and pit on the other, "

That is the textbook example of the incorrect gap or a failed condenser.

When the points fail, what is the gap?

If the wear block erodes due to poor lube, the gap decreases and the points burn.

The correct gap is .015 on the high cam lobe.
75 Tips

 

[Hobo,NC]

Its easier to answer the short questions than get lost in the long replies... KEEP IT SIMPLE answer Bob's questions...

 

[Ron Petterson]

(quoted from post at 22:04:24 02/22/20) Since it is a series circuit, Amp reading will be the same throughout the complete circuit.

Do you have an accurate way of measuring DC Amps in the 5 Amp range?

Yes, my meter has a setting for up to 10 amps
Thanks

 

[Ron Petterson]

I will remove the distributor and check it for any apparent wear and make sure the advance springs, weights, etc are not worn or weak. Each time I have replaced the points I have not detected any movement or anything loose, but will check that again.

I have never checked the gap after they have failed. I will do that this time.

And to be truthful, I do not remember when I replaced the condenser last. I know it has been done but I know they were burning before that and after.

I have also been looking for blue streak points and i can find no one that list those locally or online for this tractor. I did get information that the company that makes Bluie Streak also owns Ecklin and those are sold at NAPA and the Blue Streak is under the Ecklin name with a "Premium" part number in their listing.

So until I followup with the ideas you have provided, let me complete that and if I have further questions, I will post those. Thanks

 

[deanostoybox]

You said:
"I have also been looking for blue streak points and i can find no one that list those locally or online for this tractor."

This site sells them, <a href="https://www.yesterdaystractors.com/Ford-8N_Distributor-Point-Set_A0NN12107ABS.html">see</a> and <a href="https://www.yesterdaystractors.com/Ford-8N_Tune-Kit-Basic_APN12000ABSR.html">as a kit</a>. I have had good luck finding N.O.S. Blue Streak points on ebay.

Recommended distributor cam lubricants are:
NAPA ECH ML1
Standard Lubricam Points Lube SL-2

You said:
"Yes, my meter has a setting for up to 10 amps"
As long as the resistor is not physically mangled and has continuity it is very likely OK and not your problem. If you want to do the experiment anyway, here is what to expect. As this resistor is designed to take advantage of the change in resistance due to change in temperature in order to give a "boost" during cranking, the resistance is low when cold and increases as the resistor heats up. With the ammeter in series with the resistor and coil and the points closed, when the switch is first turned on the current will go to its highest level which will be somewhere around 5 Amps. Then it will drop quickly at first, then more slowly as the resistor heats up until it stabilizes at somewhere around 2 to 2-1/2 Amps. That is the behavior of a good healthy OEM style ballast resistor for the N series tractors with a front mount distributor.

The mechanical and electrical causes for burned points have been covered by others. There is one more thing that can cause points to burn up prematurely. That is contamination. Contamination can be caused by excessive distributor cam lubricant, dirty feeler gauge, touching the contact surfaces with a finger, or cleaning the points with sandpaper, emery cloth, or anything else that is not clean. Also using carburetor cleaner or brake cleaner to clean points or feeler gauges is not a good idea. Best to use alcohol or electric parts cleaner. Other sources of contamination on the front mount distributor are dust dirt oil and moisture getting in due to worn, broken, or missing <a href="https://www.yesterdaystractors.com/Ford-8N_Distributor-Gasket-Kit_9N12104.html">gaskets</a>. Some distributors have a vent hole with a brass screen. Some don't. If yours has the vent hole with the screen, make sure the screen is clean. Ventilation is a good thing. If yours has the vent hole and the screen is missing, plug the hole. It is better to not have ventilation than it is to have a hole that dirt, oil, moisture bugs and spiders can get in and mess things up.

And now a story.
Fella the lives down the road a ways has a 2N he uses to mow a few acres with. About three years ago he stopped by saying his tractor had stopped in the field and had no spark. He complained that he had been replacing point very often as they seemed to burn up quickly. He said he was using good quality points and had replaced the condenser etc., and could I have a look at it. I went with him to his place and we looked at the tractor and sure enough it had no spark. I removed the distributor and when I opened it up I found the interior was covered in an oily film. I took the distributor apart, cleaned it up, checked everything, cleaned and adjusted the points after putting it back together. Reinstalled the cap and coil, put the distributor back on the engine. Then I checked the oil as it seemed to be leaking quite a bit. The oils was clean and fresh and at the correct level, but I noticed the dipstick tube was "muddy" with oil and dirt on the outside. I cleaned the dipstick tube, reinstalled the dipstick, and proceeded to check the oil filler cap. It was plugged solid, no way any air was getting through that. I stuffed a clean shop rag into the oil fill tube and gave him the oil fill cap and told him he needed to get a new one. He brought me home and dropped me off and headed into town for a new oil filler cap. Saw the guy a couple of months ago and he told me the tractor is running fine and he has not had to touch the distributor. My thinking is that the engine was building up a little bit of crankcase pressure and pushing some oil into the distributor. You never know.

 

[Ron Petterson]

Thank you for this information! I well add it to my list of things to do. And I have not noticed any oil residue in the distributor, but checking the oil fill cap is not part of my maintenance. Good recommendation. Thanks