Going crazy with ignition problems

[dbsoundman]

OK folks, I have a 1948-49 8N with a front mount distributor. Got it from a buddy, it was his dad's tractor, last run around 2020. Buddy kept it covered so it was in relatively good shape, and he also put paint on it whenever he had some out and about, so it's pretty layered up with Ford red paint.

When I first got it, it had a Pertronix ignition system and wouldn't start. I put some new plugs in it, messed with it for a few hours, then we just pushed it on the trailer. He also gave me a ton of extra parts, including distributor points, some rotors, caps, capacitors, all kinds of ignition bits and bobs.

Prior to this, I had a 9N I got from him that was running with a brand new distributor, cap, and coil, and a rebuilt carb (meaning I replaced the needle and seat, and whatever other parts came in the TSC rebuild kit). I futzed around with the 8N for a few Saturday afternoons but never could get spark, and I wasn't convinced I was getting good fuel flow through the aftermarket fuel shutoff valve (no bowl or filter). I replaced ignition wiring and checked the side mounted coil resistor and all seemed well. Tried the coil that came with the 8N, various cap, rotor, distributor combinations, no love.

After the holidays, I decided to just go for broke and I took a bunch of good parts from the 9N to put them on the 8N, including a steel fuel line, the rebuilt carburetor, and new distributor, cap, and coil. Futzed around for another weekend but didn't really get anywhere. I also got several fuel bowl assemblies from my friend so I took one and rebuilt it with a fresh O ring as it leaked like crazy when I first tried it out. At this point I knew I had good fuel flow, as I could flood the carburetor if I choked it for too long. I have a spark tester and was checking for spark, and I was getting good spark at this point. When I FINALLY got it running last weekend, I put the original carburetor on it after I gave it a workbench cleaning and look-over (the float floats just fine, needle and seat were moving good), and I was using the brand new distributor, cap, coil, and rotor. However, it wasn't running quite right, it was periodically backfiring through the intake, and wouldn't run below about 1/2 throttle.

Did some more reading, and backfiring issues seemed to point to more ignition issues, so today I took off the distributor to see how it looked. The new distributor (which I did nothing to when I first got it except slap it on the tractor) has a really small points gap; smaller than 0.014, I didn't go any lower. I can't really get it to open up any further by adjusting the screws inside; I loosened the top and bottom screws and used the one in the middle with the cam on it to see how far I could get it to move out. I had put a new set of points on what I believe to be the original, pre-Pertronix distributor for this 8N, so I checked the gap on that one, set it to 0.015, gave everything a clean up, replaced the capacitor with a new one I had in the parts box, cleaned all points of contact in the cap and rotor, and put it all back on the tractor. I ran out of time today before I could do more detailed diagnosis but it seems like now I am getting no spark at all, or very weak spark. I cranked it with choke and gas came out of the carb but I didn't get so much as a single pop.

I'm beginning to feel like I'm running in circles here and burning a ton of time on what seems to be a very very simple system. At this point I think the only other things I can try is new spark plug wires, even though that rarely seems to come up in troubleshooting processes, or maybe a different ballast resistor? The plugs are carbon fouled from all the cranking I've been doing, I guess I could clean them too? Just looking for some encouragement and advice so I don't just say to heck with it and save up for a diesel tractor.

 

[HarryVanderpool]

dB, you are running around in circles.
Try to take a systematic approach.
For now, forget about getting it running.
Rather, because you know that you likely have multiple and overlapping problems; focus on one thing at a time.
Conduct a comprehensive compression check. If readings are adequate, then:
I would start with ignition because this is verifiable statically, without regard to "running"
When you have verified good, hot spark, on time, move onto fuel system.
Start at the beginning making sure all 3 fuel filters are clear, fresh fuel and adequate fuel flow using the carb drain test.
One system at a time. You can do it!!

 

[dbsoundman]

dB, you are running around in circles.
Try to take a systematic approach.
For now, forget about getting it running.
Rather, because you know that you likely have multiple and overlapping problems; focus on one thing at a time.
Conduct a comprehensive compression check. If readings are adequate, then:
I would start with ignition because this is verifiable statically, without regard to "running"
When you have verified good, hot spark, on time, move onto fuel system.
Start at the beginning making sure all 3 fuel filters are clear, fresh fuel and adequate fuel flow using the carb drain test.
One system at a time. You can do it!!

Thanks harry. I did leave out some details, I’m confident in the fuel delivery system now because I have gone through all the filters and components there. I need to get a compression tester for my own sanity. But I will check spark on each plug. I’m actually wondering if that white external ballast resistor is playing with me…

Oh also the ignition switch is new, the key switch was bad so I put in a regular toggle switch for now. I’m just vexed that such a simple system is requiring so much diagnostic work.

 

[Lynn Patrick]

Oh also the ignition switch is new, the key switch was bad so I put in a regular toggle switch for now. I’m just vexed that such a simple system is requiring so much diagnostic work.

I once bought an 8N from a country "mechanic" who could not get it started. He had replaced the key w/a toggle just as you did, only he had replaced it w/a faulty toggle switch. That's all it took for me to get that one running!

 

[Jim L WA]

DB, unless I keep missing it, you never said if the 8N is 6 or 12 volt. But you did mention a side mounted coil resister. I'm just wondering if that coil resister is needed or is causing a week spark. Also with all your work replacing distributors make sure the firing order in correct. One more thing, condensers can be bad right out of the box.
Keep us up to date.

 

[dbsoundman]

DB, unless I keep missing it, you never said if the 8N is 6 or 12 volt. But you did mention a side mounted coil resister. I'm just wondering if that coil resister is needed or is causing a week spark. Also with all your work replacing distributors make sure the firing order in correct. One more thing, condensers can be bad right out of the box.
Keep us up to date.

I checked spark today visually, all plugs are carboned up but have bright purple white spark. I verified firing order with a multimeter. This is a 12 volt tractor. I also tried with the resistor bypassed today. I don’t have a compression tester yet but putting my hand over the hole while cranking each port had what felt like the same amount of pressure coming out.

I just can’t believe it’s this complicated. I even tried a newer starter today. It turns faster, but still not even a single pop.

 

[Jim L WA]

I checked spark today visually, all plugs are carboned up but have bright purple white spark. I verified firing order with a multimeter. This is a 12 volt tractor. I also tried with the resistor bypassed today. I don’t have a compression tester yet but putting my hand over the hole while cranking each port had what felt like the same amount of pressure coming out.

I just can’t believe it’s this complicated. I even tried a newer starter today. It turns faster, but still not even a single

So, you have good spark at the correct time. What have you changed since you said you got it running the other day, but it wouldn't run under half throttle? One other thing, How old is the gas?

 

[dbsoundman]

So, you have good spark at the correct time. What have you changed since you said you got it running the other day, but it wouldn't run under half throttle? One other thing, How old is the gas?

Fuel is a good idea. I ended up using the gas from my 9N, which is kind of pink because of the marvel mystery oil I added to it. That gas is less than a year old and it’s non ethanol fuel. Nevertheless I can definitely grab some fresher fuel.

When it ran a couple weeks ago, it idled in the shop for a while at maybe 3/4 throttle then I took it for a drive. When I stopped to switch from 2nd to 3rd and tried to take off in 3rd it died and wouldn’t restart. I ended up towing it back to the barn and didn’t really check on it for a couple weeks. At that point I realized it was out of fuel, so it was either low on fuel or the fuel slowly leaked out, this was before I refurbished the fuel bowl.

 

[dbsoundman]

Oh, and what changed since the last time it ran in the shop: not sure. It ran in the shop for a little while and died when I tried to idle below 1/2 throttle, and it hasn’t started since. I’ve swapped the carb today, and checked the full ignition system today as stated.

 

[used red MN]

From your opening post:

At this point I think the only other things I can try is new spark plug wires, even though that rarely seems to come up in troubleshooting processes, or maybe a different ballast resistor? The plugs are carbon fouled from all the cranking I've been doing, I guess I could clean them too?

From your reply number 6

I checked spark today visually, all plugs are carboned up but have bright purple white spark.

Spark plugs rarely come up in troubleshooting processes?? (see edit below) You have missed the boat!! A little explanation might help you.
The first auto mechanic shop I worked at was sold a sort of a “gimmick” tester. One of the things it did was produce a continuous spark out of a test probe. The spark wasn’t like would come out of a coil it was more like a static electricity spark. Even though it could jump a 1/2 inch or more if you weren’t really put off by an electric shock you could jump the spark right into the palm of your hand and it was nothing more than a bit uncomfortable. That thing showed me about carbon fouled plugs. When carbon fouled, the spark jumps from the electrode in the center of the cone shaped porcelain right over to the carbon on the cone. Then it follows a jagged path down the carbon covered cone to the metal surround it mounts to in the base of the plug. It can fire the mixture but it does a far less adequate job then it does jumping the gap that is sticking into the combustion chamber as it was designed to. And to add to that I was observing the plug reaction to this spark machine in an open atmosphere. If you didn’t know a plug has exponentially more difficultly firing under pressure.
Your discounting the carbon fouling on the plugs is part of what has been chasing you in circles. When you said at one point you got it running but it wasn’t running right my guess would be if the plugs would have been clean and firing properly you would have been done.
A method I use to clean plugs is clamp it in a vise plug wire end down, give it a squirt of carb cleaner take a wire brush to it. Add a motion sort of like your hammering the end of the plug with the wire brush so the wire ends protrude down in around the porcelain cone. Blast with compressed air and I suggest wrapping a rag around it to catch all the black gunk that will spray everywhere. THEN REPEAT!!
Edit: Sorry if I came on strong. I see you actually said “spark plug wires don’t come up to often in troubleshooting processes” The spark plug info still very much applies.

 

[dbsoundman]

From your opening post:


From your reply number 6

Spark plugs rarely come up in troubleshooting processes?? (see edit below) You have missed the boat!! A little explanation might help you.
The first auto mechanic shop I worked at was sold a sort of a “gimmick” tester. One of the things it did was produce a continuous spark out of a test probe. The spark wasn’t like would come out of a coil it was more like a static electricity spark. Even though it could jump a 1/2 inch or more if you weren’t really put off by an electric shock you could jump the spark right into the palm of your hand and it was nothing more than a bit uncomfortable. That thing showed me about carbon fouled plugs. When carbon fouled, the spark jumps from the electrode in the center of the cone shaped porcelain right over to the carbon on the cone. Then it follows a jagged path down the carbon covered cone to the metal surround it mounts to in the base of the plug. It can fire the mixture but it does a far less adequate job then it does jumping the gap that is sticking into the combustion chamber as it was designed to. And to add to that I was observing the plug reaction to this spark machine in an open atmosphere. If you didn’t know a plug has exponentially more difficultly firing under pressure.
Your discounting the carbon fouling on the plugs is part of what has been chasing you in circles. When you said at one point you got it running but it wasn’t running right my guess would be if the plugs would have been clean and firing properly you would have been done.
A method I use to clean plugs is clamp it in a vise plug wire end down, give it a squirt of carb cleaner take a wire brush to it. Add a motion sort of like your hammering the end of the plug with the wire brush so the wire ends protrude down in around the porcelain cone. Blast with compressed air and I suggest wrapping a rag around it to catch all the black gunk that will spray everywhere. THEN REPEAT!!
Edit: Sorry if I came on strong. I see you actually said “spark plug wires don’t come up to often in troubleshooting processes” The spark plug info still very much applies.

No offense taken, I’m very glad you added this info. The carbon seemed like it could be an issue but I wasn’t sure because the spark looked good. I’ll clean them up next chance I get. I gave them a quick clean with brake cleaner and a a toothbrush but that didn’t get too much off.

 

[Jim in LA]

You may want to check the mechanical spark advance in the distributor base underneath the points breaker plate. You also may need to go to N Tractor Club forum , How To section, Electrical and look up wiring diagrams JMOR. lots of good stuff on there.

 

[dbsoundman]

Here’s what the plugs look like. That’s all carbon.

 

[used red MN]

Here’s what the plugs look like. That’s all carbon.
View attachment 142177

Not the best photo for reading spark plugs. The ones that have that kind of almost powdery/flaky carbon/soot on the top flat part of the porcelain cone could very well fire/short down the porcelain as I talked about on reply 10. Second one from the bottom seems to be the best example.

 

[HarryVanderpool]

It doesn't look like carbon to me.
Looks like oil fouling.
But it's a picture.
Take the worst and rub the plug against the open palm of yor hand.
Does the residue wipe off as a powder, or leave an oily stripe?
Looks like oil to me.

 

[used red MN]

It doesn't look like carbon to me.
Looks like oil fouling.
But it's a picture.
Take the worst and rub the plug against the open palm of yor hand.
Does the residue wipe off as a powder, or leave an oily stripe?
Looks like oil to me.

I could be convinced of that. The second one from the top where the porcelain cone shows a cleaner white area towards its bottom orientation in the photo is indicative of oil coming at the plug from the opposite side.

 

[Eman85]

Buy a spark tester and 4 new spark plugs for after you confirm good spark. Do a real spark test. On a tractor that won't start if the plugs are wet they are gas fouled.

 

[used red MN]

Do a real spark test.

dbSoundman, This means an adjustable gap spark tester set to a 1/4” gap, see example tester in link. If you didn’t catch it, it takes more voltage/a better spark to fire a plug when it is under pressure from compression. That is why jumping the 1/4” gap on an tester assures the ability to fire the plug. Example spark tester

 

[Jim L WA]

Dbsoundman said he put new plugs in. If those photos are of the new plugs, how did they get that fouled? If that is carbon, then it's running way too rich, if it's oil, well, there are other problems.

 

[HarryVanderpool]

There is nothing wrong with those plugs other than fouling. Clean, gap and work systematically through the machine to diagnose.