1949 8N - I am utterly, completely, 100%, stumped...

[Captain Ledd]

Dad is yelling at me to get some of the other projects out of the barn before I start new ones, which I suppose is fair.

So I dig out the old 8N that the engine was "rebuilt" by me and him nearly 10/12 years ago now. I never got to finish it, he had some health problems, I had left for college by the time he was better, so there was several years between disassembly and reassembly.

The problem:

We've got it down to weak/intermittent spark.

The engine won't even "pop" when using starter ether, at all. It's as if nothing is happening.

Originally started out as no spark. Dad was told years ago by an "expert who knew everything" that we didn't need the ignition coil resistor. Some old farm hands I talked to more recently said, "oh hell yes you need that, you'll burn out your points and coil in a jiffy". And that set in motion the list of new parts.

Replaced ignition coil resistor - no spark

The we did points (yes, they were very dead)- VERY intermittent spark, and very weak.

so we figured, the coil looked pretty old, could have been damaged, replaced that - slightly more consistent spark, VERY weak.

Dad ran panel wires for a number of years for assembly line robots. SO the wiring is good.

Checked spark with a spare spark plug wire, worked alot better.
*this was a modern high energy plug wire, which I was also told shouldn't/doesn't work near as well as the old style copper core wires*

Wires were old too, so we got a set of new wires (copper core wires). They're trim to length, but we've checked the conductivity for all of them, and all have been making good contact. (slightly more intermittent spark, weak when it does spark)

The book said .015 gap for a front mount distributor (ours), we checked it and found that we had nearly 90° of crank rotation with the points closed.

re-gapped for .025 (angle distributor spec) and now have 5°-10° crank rotation with points closed.

NOW it changed, it sparked good the first time around, 2nd time around it was very weak, then it disappeared entirely and hasn't returned. Yes, the points were tightened down.

The cap is new and the rotor is also new.

It still doesn't pop or make any indication that something is fireing in the cylinders.

Cylinders 1,2,3 are at about 90 psi (minimum), 4 is at 80 psi. which would probably run a little wierd, but not cause NOTHING to happen at all.

The timing has been checked, checked again, and rechecked a third time. Compression shoots up and when the plug does decide to fire, it's immediately after the compression tops out.

The regulator is the only electrical thing we haven't replaced, though it's not even hooked up at the moment. We're desperately trying to just get it to make some kind of noise, anything.


The annoying part? When it was running there was no cylinder head gasket between ANY of the cylinders. It brush hogged and plowed.

After replacing the head gasket, it began belching out exhaust and burnt oil smoke out the oil fill cap, which meant the rings were gone and thus lead to the rebuild. Still, it RAN and brush hogged and plowed.

I'm out of ideas. I've tried every form of reasonable diagnosis I can think of... ANY help would be appreciated. Everything I can think of that would help I've already tried.

 

[Earl43P]

Maybe the starter is pulling all the amps and coil doesn't get enough juice.

Can you hook some jumper cables or an additional battery, see how that helps?

With all that work, you had to have run the battery down (and probably have already jumped it, but I had to say it).

 

[Captain Ledd]

Haven't jumped it, generally I fiddle with it for a good 30-45 minutes and let it sit on the charger. I may pilfer the battery out of my neighbors Willy's and rig a dual battery setup. I had some doubts about the battery in the first place, but it seemed to work ok.

It's doubly interesting about the starter because the thing has been getting "stuck", and we have to give the engine a few cranks by hand (key off mind you) and a couple whacks to the starter motor to get it to move again. I wonder if it's eating more juice with some extra resistance.

But yeah, it's pretty much spent the last few days constantly on the charger, either on 6 amps (while we're messing with it) or on 2amps (left on usually overnight).

Oh, and it shows 6.5 volts.

*edit:

THOUGHT! I just remembered while thinking about the battery, I've heard dead cells can sometimes show full voltage, but drop off the planet while under load... Maybe I'll check for that tomorrow.

 

[85_Ranger4x4]

If you have a 12v coil (provided it has been converted to 12v) you won't need a resister, if it is still 6v you won't need the resister either (they didn't originally come with them) If you have 6.5 volts at the battery it must still be 6v or have a deader than dead 12v battery, so lose the resister if it is 6v.

Only a 6v coil on a 12v system needs the resister so the ignition system only sees the 6v it was made for.

When you changed points did you change the condenser too?

Hook the regulator up too, sometimes they either need to be hooked up or properly bypassed for the engine to run.

 

[Captain Ledd]

Nope, 6V coil. That's what the box said.

Edit: Yes I changed the condenser as well, it came as a small kit.

Still all the original style 6V parts, just newer wires run to things.

This is the resistor:

Although mine has alot less wire too it and not nearly as tight a weave.

The tractor has never had a 12V battery in it, and we've had it for a good 25 years. It's always had a resistor in it too (the old one got broken somehow during the years disassembled).

The wireing diagrams I have also show that resistor as original equipment.

Edit again:

Been doing some more reading and asking around. Apparently I'm supposed to be getting 3-4V at the coil? I'm getting battery voltage.

 

[85_Ranger4x4]

Nope, 6V coil. That's what the box said.

Edit: Yes I changed the condenser as well, it came as a small kit.

Still all the original style 6V parts, just newer wires run to things.

This is the resistor:

Although mine has alot less wire too it and not nearly as tight a weave.

The tractor has never had a 12V battery in it, and we've had it for a good 25 years. It's always had a resistor in it too (the old one got broken somehow during the years disassembled).

The wireing diagrams I have also show that resistor as original equipment.

Edit again:

Been doing some more reading and asking around. Apparently I'm supposed to be getting 3-4V at the coil? I'm getting battery voltage.

Ok, must be a Ford deal. I have never really done much with them, I have only really messed with John Deere and A-C and since they are both similar I figured Ford would be too. Here is what the resisters look like I was thinking about, Dodge used them for quite awhile from the factory to accomplish the same thing when they went to 12v:

You might check the resister to make sure it is resisting to the proper level, some of the parts they are making for older stuff is kind of sketchy. Just having a new one doesn't mean it is a good one. We went thru 3 regulators to get a good one for a Ford 850 we had in the shop awhile ago. I dabble with them on the side, I only work in the parts dept at the shop.

Make sure the wiring is right on the regulator, it probably has to be wired for everything to work right. Again it was with a Deere, but my brother's B was dead in the water without it hooked up.

If you haven't tried it yet, there is a wealth of information on yesterdaystractors.com.

http://yesterdaystractors.com/

 

[martin]

Don't know if I'll be of much help but here goes. The resister is used to reduce coil voltage after the motor is running, the coil is supposed to recieve full voltage during the cranking process. This is to counteract so of the voltage drop caused by the starters heavy draw on the system.
I would suggest setting the points with a degree wheel to obtain the correct dwell on the distributor, ninety sounds like too much and ten is definately too little. It might also be an issue with the condensor, they can deteriate with age and the new one you put in might be as old as the one you took out.
As a last resort you could always screw a tfi module onto a heat sink and use the points to trigger it.

 

[85_Ranger4x4]

Don't know if I'll be of much help but here goes. The resister is used to reduce coil voltage after the motor is running, the coil is supposed to recieve full voltage during the cranking process. This is to counteract so of the voltage drop caused by the starters heavy draw on the system.
I would suggest setting the points with a degree wheel to obtain the correct dwell on the distributor, ninety sounds like too much and ten is definately too little. It might also be an issue with the condensor, they can deteriate with age and the new one you put in might be as old as the one you took out.
As a last resort you could always screw a tfi module onto a heat sink and use the points to trigger it.

I did some looking at diagrams and this isn't like how you use a resister in a Duraspark conversion, it is constantly going thru that resister to the coil, not just at startup.

The earlier 8N wiring diagram with the resister is on page #2.

http://ntractorclub.com/howtos/pdfs/Wiring_Diagrams_for_Ford_Tractors.pdf

 

[BRUTUS_T_HOG]

i didn't read any of the posts above, but what kind of voltage are you seeing at the coil positive terminal while cranking? how do you have your resistor wired up? the resistor should be bypassed and full batt. voltage ran to the coil when cranking.

also you need to put a test light on the negative terminal of the coil and see if it blinks when cranking

 

[85_Ranger4x4]

i didn't read any of the posts above, but what kind of voltage are you seeing at the coil positive terminal while cranking? how do you have your resistor wired up? the resistor should be bypassed and full batt. voltage ran to the coil when cranking.

also you need to put a test light on the negative terminal of the coil and see if it blinks when cranking

No, it should be ran thru the resistor full time, not just when running.

 

[BRUTUS_T_HOG]

No, it should be ran thru the resistor full time, not just when running.

im saying it needs full batt. voltage when cranking.. batt. voltage is low when cranking.

 

[85_Ranger4x4]

 

[BRUTUS_T_HOG]

i didn't bother to look at any of the posts, i see what you're saying from looking at the wiring diagram.

but i still say full battery voltage during cranking will improve spark. it won't hurt anything.

 

[Captain Ledd]

Well I had a rather lengthly reply, but my computer literally re-booted just as I was finished proof-reading it.

Since I'm not retyping all it again, I'll just post the short version.

The wiring diagram 85_Ranger4x4 posted is spot on to our tractor.

That special little resistor seems to be a rather hot topic from what I've found. Though there is a much stronger case (I feel) that it is very much required.

I read an article about "jumping" 6V systems with a 12V battery. I have the extra heavy wires to do it and will likely try that tomorrow. I like it better than the dual 6V battery setup I was imagining, and then it will allow the 6V battery to devote its full energy to the coil.

Also read that standard automotive plugs don't always work as well. And I should use either Champion H12's or Autolite 437's. I have no idea what's on there right now (it's midnight atm), but I do know they're gapped correctly.

I'm going to re-check the points. Maybe adjust them a tad closer. Also going to spend alot of time with the meeter checking connections in there as well as other places. The picture 85_Ranger4x4 posted will hopefully help out with that as well, since it lists voltages I can check against.

Found out the ignition key will come out just as easily in the ON position as the OFF position. While the key tested good, this bothers me, and I'll likely replace that with another unit or maybe even with just a big toggle switch. Let's face it, in terms of hot-wire-ability, these things are among the easiest. It lives in a locked shed anyways.

That Yesterdays Tractors site is awfully useful, I'm gonna have to spend some time poking around there. Alot of the links I found were from that site anyways.

Sooner or later I'm gonna find what it is...

 

[85_Ranger4x4]

If you are getting full battery power at the coil (and you say you shouldn't), jumping it with a 12v battery won't help get more power to it.

Our Champion book calls for H12 plugs gapped to .025.

Personally I wonder if a faulty resister fried the points.