stubborn 8N

My 1948 8N has ignition trouble; not firing. It had been cutting out this summer when it got warm, and then shutting down. I tuned up the electrical by replacing plugs, distributor cap, points, rotor, condenser, and ignition resistor. Still cut out at higher rpm, under load, after working for quite a while in warm or hot weather. Then one day in August, it just quit. Haven't been able to get a spark to the plugs since. Troubleshooting in the operators manual, and in the shop manual, all indications are that the problem is in the coil or distributor parts. So my next step is to go get a new condenser and replace it, but now I'm just grasping at straws. Any ideas as to what I'm missing here?

Start with the basics. No need to buy more parts yet.
Need to know if its 6 volt or 12 volt to give you numbers, but....
Does it have battery voltage to the coil when the points are open (key on)?
If not, what is the voltage there?
If zero, you're looking back toward the switch and wiring.
If a little less than battery voltage then you may have a ground in the distributor.
If it is battery voltage there with points open, what is it with the points closed?
If its still battery voltage, then the points are not making contact and may
just need to be cleaned and adjusted.
When you say you replaced the ignition resistor, do you mean the original ballast resistor?
The one on the back side of the dash?
If so, did you replace it with the same type?
The white ceramic ones don't have the same electrical characteristics.

Royse has it about right. Failure to trouble shoot it will only result in you throwing money at it till you guess the bad part.

I throw in a few other questions.

Where did you buy parts at? The problem could be that. Blue Streak and NAPA (premium NAPA not the cheap stuff) are the prefered ignition parts.

Search the arcives for Burce's 50 tips and print them out. Follow em!

Did you run a jumper past the ignition switch to eliminate that?

My guess from what you describe from both before and after your tune up would be A. The switch B. the coil. Cutting out a high RPM's and dieing and failure to restart while still hot is a symptom of a coil issue. C. wrong resistor and D. cheap parts.

Rick

There are two schools of thought when it comes to getting a non-running tractor to start. One way is to just start replacing every part you can get to until it starts or you run out of money. The other way is to take a step-by-step approach to solving the problem, working from most likely to least likely. The trick to fixing these tractors (or trouble shooting any piece of equipment) is to be systematic about it. You need to isolate the problem step by step and work from most likely to least likely. You have solved half the problem by determining it is a spark problem. As others have just said, that doesn’t mean you need to replace all of the electrical parts on the tractor!

I'll save you some money......it's highly unlikely that you have a bad coil or condenser. What you do have is poor troubleshooting skills. We can help w/ that.

Before you check anything else, make sure you have the correct voltage at the top of the coil. It should be battery voltage w/ the points open & about half that w/ the points closed.

Assuming that the bushings & advance weights are ok, & that you have correct voltage to the coil, the most common electrical failure (no spark, weak spark) points on the frontmount are:

1. The insulator under the brass concave head screw & where the copper strip attaches. (it’s fiber & will wear out; poke & prod w/ your meter leads to make sure it still works)

2. The pigtail at the bottom of the coil not making contact w/ the concave head brass screw inside the distributor. (With the coil on, the pigtail must firmly contact the brass screw. No contact = no spark.).

3. The copper strip is broken or grounded to the plate. (look very carefully for cracks & breaks)

4. The condenser wire grounding to the plate or side of the distributor.

5. The tab on the bottom of the coil not making contact w/ the brass button on the cap. (With the cap on, the tab must firmly contact the brass button. No contact = no spark.)

6. Incorrect positioning of the spring clip on the plate causing the pigtail to ground. (the open part of the clip goes between 7 & 9 o’clock on the plate. That puts the straight part of the clip opposite of the timing screw at 3 o’clock)

7. Incorrect seating of the coil on the distributor due to a loose bail or no gasket.(the coil must not move at all; if it does, replace the gasket or bail. Or stick some cardboard under the bail).

8. Water/moisture inside the cap due to gasket failure or the absence of a gasket. (the cap AND coil have gaskets)

9. Dirty/corroded/burned/incorrectly gapped or misaligned points.

10. Burned rotor, cracked/carbon tracked cap.

Unless the coil is cracked or shows a dead short, chances are it's fine; square coils rarely fail cold. Pull the distributor & do a continuity check.

First, make sure your meter/light works (don't ask....)

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.

Inspect the points; if they are pitted or burned, replace them. Next, dress the points by running a piece of card stock or brown paper bag through them. New points sometimes have an anti-corrosive dielectric coating on them & old points can corrode or pick up grease from a dirty feeler gauge or excessive cam lubricant. 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. Then, check the gap at .015 on the high point of all 4 cam lobes.

Now, follow these steps:

1. Coil off, cap off, points open. One probe on the brass screw & the other on both sides of the open points. On the side closest to the cam, you should have continuity. Not on the other side! If you do, you will also have continuity everywhere because the points are grounded.

2. Coil off, cap off, points open. One probe on the brass screw & the other anywhere on the body of the distributor. You should have no continuity! Now, rotate the tang on the distributor....as the points open & close, you have continuity (closed) and lose it when they open.

3. Coil on, cap off, points open. One probe on the lead on the top of the coil, the other on the cam side of the open points. You should have continuity!

4. Coil on, cap off, points open. One probe on the lead on the top of the coil, the other anywhere on the body of the distributor. You should have no continuity!

At this point, I just put the distributor, coil & cap all back on the tractor as a unit. The reason I do this is because it is real easy to get the cap or coil mis-aligned trying to put it back together one piece at a time & the result is something gets broken or you get a ‘no spark’ problem.

It's possible to put it back on wrong & break it. Look at the slot on the end of the cam shaft. What ever angle it happens to be, turn the distributor tang to match it. Make sure you can tell the wide side from the narrow side on both the cam & distributor! (close counts) Then place the distributor on the front of the engine, gently push it in place & slowly turn the distributor body until you feel the tang slip into the slot. Rotate the distributor body until the bolt holes line up. Then, hand tighten the two bolts until the distributor body is flush w/ the timing gear cover.

Finally, double check your firing order & plug wires. It’s 1-2-4-3, counterclockwise. It’s very easy to cross 3 & 4.

Post back w/ answers to our questions; we can help you get it running.
50 Tips

The one thing that everyone has hinted at; but, not touched directly is; "buy quality parts!"
My biggest problem getting my '48 8N up and running is cheap parts. Points that don't line up and aluminum parts (points backing plate) that should have been steel or something else other than aluminum.
Enough people have posted p/n's for NAPA brand parts. find a list on here and copy it down for reference.
New doesn't always mean better.
Good luck.

Having never contributed to the forum before, I wasn't sure how to reply back to my advisors. So I'll just post this way and see if it works; to Royse, old tanker, and BruceVA: Thanks for the excellent tips. I was more than a little embarrassed to be labeled a poor troubleshooter, after being an aerospace ground equipment mechanic in the AF for 9 years, but it is true. This little tractor has some weird habits, and I am no expert on it, for sure. I did tune it up because it needed it, so I don't think I bought unnecessary parts. Yes Royse, when I looked at the parts catalog, I made sure I got the same ballast resistor listed for my tractor, and the only reason I suspected it might be an issue was that the bakelite was crumbling so bad that it was hard to keep nuts tightened down on the screws. I had already checked the switch, but when I moved on to the coil (it's a 6 v) it had batt voltage. It had battery voltage at the condenser and points connection to the brass screw. Points open or closed, so checked the housing; same thing. I didn't think I would get battery voltage if it was grounded out, but here was my evidence. So checked out the insulator that Bruce had suggested might be worn out at the brass screw, and it is crumbling, so consequently shorting out. So what now? The breaker plate looks like a part that has to be remanufactured, but not in a home shop. The shop manual (I bought the I&T one when I bought my tractor, along with the N's operators manual published by Ford) has the breaker plate PN as 9N12151, and all I could find in ytmag was PN 9N12150 and says it's for all 8N's with a front mounted distributor. From what I could tell, they are the same; not sure why they are different by one. Another question within a question; there's an electronic ignition conversion that would fit in this distributor; does it need that insulated connection, or would it bypass it; I am not familiar with how they hook up? I think I'm going to hold off on ordering the breaker plate until I hear back from one of you guys. Thanks again for your tips. By the way, oltanker's tip to get Bruce's 50 Tips was a good one; first thing I did when I got your replies was to print them off and put them with my manuals.

" So what now?"

Replace the insulator w/ a square nylon anchor nut. Check out the link below.

" It had battery voltage at the condenser and points connection to the brass screw. Points open or closed, "

Which means you have a dead short, as I said in my continuity check list.

If you do not want to try replacing the insulator, just replace the entire plate for $35 or so. But save the concave head brass screw because the replacement plates do not come w/ them.

"Another question within a question; there's an electronic ignition conversion"

Why? You can fix it w/ the nylon anchor for $1. And quality points correctly installed. EI will not work well at all on 6v (it won't fire below 5.2v) so you would need to convert it to 12v.

EI does not give you higher spark voltage, eliminate all maintenance on your ignition system or give enough of a horsepower boost to cause the tractor to do wheelies. It replaces the points. That’s it. It will not correct or overcome other problems in the ignition system. While it may give you more HP or improve fuel economy, both would be so insignificant as to be hardly noticeable on a 23 hp engine. If you can’t set points or don’t care to do it, or you don’t want to spend the 30 minutes or so a year to check the gap & lube the cam, then you will be happy w/ EI. And, the EI unit itself will be maintenance free. (but the rest of the ignition system won’t) You will spend probably $235 for an EI kit & 12v conversion. If you install them correctly you will have an easy starting tractor for a long time. And, the 12 volt conversion & EI will have just about nothing to do w/ the good performance. What will make the real difference is the new wiring, cables, clean grounds & new battery.

The key advantage to EI is that you do not need to gap & lube the points every year & replace them every 4 or 5 years or. If you perform annual maintenance on the points & change them every 4 years or so using quality parts, you will see no difference whatsoever between a points ignition system & EI on an N.

The key disadvantages to EI on an N are initial cost, nearly impossible for the average N owner to repair, will not work w/ low battery voltage, & easily damaged beyond repair by polarity reversal & other common mistakes.

Bottom line……….this is the question you need to answer: “If tens of thousands of other N’s operate just fine on 6v and points, why can’t mine?”

Your money, your tractor, your call........$1 or $240.

Please post back w/ results or other questions.
Hillman 3/8 sq nylon anchor nut

I had read enough, and had my 8N long enough, to know that I didn"t necessarily need a 12 volt system. I used to have a Ferguson TO-30, converted to 12v before I got it, and didn't notice that it started any easier or ran better than either of the Ns that I've had. And to know that I can fix the breaker plate with just a nylon nut means I can probably get this thing going this week (and I'm cheap enough that I won't spend $35 or $42 or whatever over a buck or two). I've been dinking around with old cars for over 50 years; when I had my first paid for car, it still was put together and kept running with help from local junkyard, so old ignition systems aren't exactly foreign; changing out points and distributor parts will just keep me in practice. And to know I have good help on this site, that much better. Thanks for your help and prompt reply.

There's a good number of guys here on the forum ready, willing and able to help.
I've learned a lot since I joined, and I'm still learning as I go.
If you decide to someday go to EI, I would go to 12 volts with points first.
It's a cheaper conversion, and you're not changing as many things at once.
Once you have the 12 volt conversion working, charging system etc, if you find you still need or want EI, do it then.
In any event, I would not try to convert a non-running tractor to EI. It would just add too many variables.
Bruce's steps should get you up and running in no time. If you have more questions feel free to ask.
Welcome to the forum!