1949 8N Won't Start

[Bartman1959]

I tried to start my 8N today after a few months of no use, with no luck. It turns over fine, but just won't fire. I pulled a spark plug, cranked it over, and was getting no spark. I pulled the distributor, gapped the points to .025, and put everything back together. Still nothing. I have power to the coil with key on, and power to the alternator, but no spark.
The last time I used the tractor was months ago, and then I had rebuilt the carb, new points, plugs, and wires. Now, after sitting for a few months, no spark. Looking for some great advice here guys.

 

[pmsmechanic]

If the distributor is worn or if the points are gapped too wide then the points won't close. Take a test light and hook it to positive somewhere. Touch the probe to the negative side of the coil. Crank the engine. The test light should flash off and on. If it doesn't then take the distributor cap off and set the points closer so that the test light flashes when you open and close the points.

You can also open and close the points with a screwdriver when they are closed. If there is current then there will be a small spark at the points. If you do this then take the center wire out of the distributor cap and place it close to some metal on the tractor. You should be able to see and hear the spark as you open and close the points.

If you get a small spark at the points but none at the coil then there is something wrong with either the coil or the center wire. If you get spark at the center wire but none at the spark plugs then there is problems with either the rotor or the cap or the spark plug wires. Lastly remove a spark plug and make sure that it sparks.

 

[Bartman1959]

I'll try all that tomorrow. Thanks.

I forgot to mention, it is the front mount distributor.

 

[Phillip w]

.025 seems a lititle wide, but maybe for that applications it is right. I used to set a 390 Ford at .o19. Also, how about you condenser. I have seen them go bad and drive guys crazy (me included) trying to figure it out

 

[David_Kb7uns]

Worked on one 8n one time, the advance mechanism inside the distributor had worn through the insulation on the wire going to the points and was keeping the coil grounded when the mechanism rotated, the key switch was also a problem on that tractor.

David

 

[Bartman1959]

Didn't get a chance to work on the tractor today; hopefully tomorrow.

 

[Bartman1959]

.024 -.026 is what the manual calls for.

 

[Phillip w]

.024 -.026 is what the manual calls for.

Better stay with the manual. I had an old ford pick up i use to set at .019. That is were I got the number

 

[pmsmechanic]

Better stay with the manual. I had an old ford pick up i use to set at .019. That is were I got the number

Except if the lobes on the distributor are worn and a wider gap won't let the points close. Then you need to set the gap closer so that they will close. That's why I suggested to check at the coil with a test light.

A tight gap on a slow running motor won't matter. Point gap affects two things. Timing and how long the coil gets to saturate with electricity. All 4 cylinder engines have very similar point gaps. 6's and 8's each have their own common point gaps also. As the number of cylinders increases the gap gets smaller. The more cylinders on a motor the closer the gap as there are more lobes on the distributor. We are trying to get it running. Not give it a tune up. After it's running and we know why it didn't start then we can work on the finer points. (Pun intended)

 

[Bartman1959]

I'll try to get out there today and check the coil with a test light.

 

[My Gym]

It has been 30 years since I have dealt with points. One of the problems was dirty , oxidized points. Try cleaning the points with fine sand paper. A film of oxidation on the contacts can create enough resistance to cause a weak or no spark. Also the arcing on the gap can create a point on the gap that will cause an incorrect gap setting. Also clean rotor and distributor cap. Oxidation on them can also cause problems. The wiping motion of the engine running keeps them clean when running

 

[Bartman1959]

I pulled the coil off and stretched the spring a little, then extended the bent contact a little, put it all back together and it fired right up. It idled for about 4 or 5 minutes and died. I haven't been able to get it restarted. Yes, I turned the fuel ON.

 

[bigdeano]

Like someone said, the points can get corroded. Use fine sandpaper on both points, then run a clean rag between them to remove any junk. I have to do it on my MM every spring after it sits all winter.

 

[Phillip w]

I pulled the coil off and stretched the spring a little, then extended the bent contact a little, put it all back together and it fired right up. It idled for about 4 or 5 minutes and died. I haven't been able to get it restarted. Yes, I turned the fuel ON.

I believe I would start getting suspicious of that coil and condenser. I'd run an ohm meter on that coil. I can't remember the readings, 7500 seems to ring a bell. I had an old 390 Ford that gave me a merry fit. It would run good for 5 minutes or so and quit. No start. Come back later it might start or it might not. Then it would start and you think you had it and it might run an hour or two and then quit. No start. An old timer told me to "throw that condenser and coil as far as I could through them and get new. If that didn't work call him back." I called him back wanting to know why it worked. He said that the condenser was probably "off a few micro-farrads thus creating problems for the coil. Thus the coil would get hot and open up. When it cooled off it might work or it might not depending on the charge and discharge or the condenser. Like I say, i tossed both and problem solved. I just can't remember the ohm readings on a good coil.

 

[Bartman1959]

I've had the battery charger on it on slow charge for a couple of days, just in case. I just went out to remove the charger and decided to "give it a try." It fired right up, ran for less than a minute and died. I tried a few more times but it didn't even attempt a restart. I didn't have time to really do anything with it today, so I turned off the key and the fuel and left it for now. I'm at a total loss here.

 

[TimberHole]

Are you sure it is getting fuel? Will it fire on starting fluid after it stalls? If not, see post 14.

 

[Tractorable]

.024 -.026 is what the manual calls for.

The points gap on a front mount distributor 8N should be 0.015.

The points gap on a side mount distributor 8N should be 0.025.

I own a '52 side mount distributor 8N.

 

[pmsmechanic]

So it started and ran. Things are looking up. How did it die? Like turning a switch off or did the engine start to sound labored and then die? Turning a switch off is fuel as a rule and laboring and then dieing is fuel.

 

[Tractorable]

Turning a switch off is fuel as a rule and laboring and then dieing is fuel.

Did you mean that if it dies like turning a switch off it's ignition and if it labors and dies it's fuel?

 

[Tractorable]

OP, did you turn on the fuel and remove the plug from the bottom of the carb? It should flow plenty of gas, enough to fill a coffee can if you wanted to.

I've had issues on my 8N with the float valve either not flowing enough gas and also with it flowing too much gas.