Coil voltage

[skyking]

Have what I believe is a '49 8N with a front mount distributor. Previous owner did a real shady 12V conversion and I've had to fix a few issues. I suspect the coil is dying a slow death as it will quit after running for a while and after sitting for a while start back up and run for a short time. It has a ballast resistor and I'm not sure if it's a 6V coil. Are there markings on the coil to determine if it's a 6V or 12V coil?

 

[Jim L WA]

Welcome skyking.
Do you have access to a multi meter? If you measure the resistance from the top of the coil to the pig tail it will till you what that coil is. Around 1 ohm is a 6 volt coil and around 2-3 ohms is a 12 volt.
Are there any other restorers between the ballast resistor and the coil?
Also just because the coil is failing doesn't mean it's wired wrong. They do break down over time.

 

[Mad Farmer]

Welcome skyking.
Do you have access to a multi meter? If you measure the resistance from the top of the coil to the pig tail it will till you what that coil is. Around 1 ohm is a 6 volt coil and around 2-3 ohms is a 12 volt.
Are there any other restorers between the ballast resistor and the coil?
Also just because the coil is failing doesn't mean it's wired wrong. They do break down over time.

That is what my coil did on an all original 6V system.

Coil was going bad. Worked OK cold weather for a couple years but died hot weather brush hogging. Eventually would not run at all.

 

[skyking]

Welcome skyking.
Do you have access to a multi meter? If you measure the resistance from the top of the coil to the pig tail it will till you what that coil is. Around 1 ohm is a 6 volt coil and around 2-3 ohms is a 12 volt.
Are there any other restorers between the ballast resistor and the coil?
Also just because the coil is failing doesn't mean it's wired wrong. They do break down over time.

I'll check the resistance but will be a couple of days before I can get back
to it. Not sure what you mean by "any other restorers between the resistor and coil"

 

[olddavid]

It could be the resistor that's opening up as well. If you have 12 volts at the coil side of the resistor when it dies then it's likely the coil or a bad connection. And yes there, should be some marking on the coil or at least a part #. Edit: I should have said 12 volts with the points closed.

 

[wore out]

Have what I believe is a '49 8N with a front mount distributor. Previous owner did a real shady 12V conversion and I've had to fix a few issues. I suspect the coil is dying a slow death as it will quit after running for a while and after sitting for a while start back up and run for a short time. It has a ballast resistor and I'm not sure if it's a 6V coil. Are there markings on the coil to determine if it's a 6V or 12V coil?

With "front mount" distributor if using a 6-Volt coil the original ballast resistor is typically kept in place and a "converting resistor" added.

If using a "12 Volt coil" the original ballast resistor remains in place.

EASY check, IF you have a suitable test Ammeter, with a fully-charged battery, read the primary ignition current with the engine "off" and the breaker points closed.

Should be 3 Amps or a bit more for a good, hot spark, and not over about 4 Amps to avoid overheating the points and coil.

If significantly over 4 Amps, "adjust" primary resistance to bring it down.

 

[Hobo,NC]

With "front mount" distributor if using a 6-Volt coil the original ballast resistor is typically kept in place and a "converting resistor" added.

If using a "12 Volt coil" the original ballast resistor remains in place.

EASY check, IF you have a suitable test Ammeter, with a fully-charged battery, read the primary ignition current with the engine "off" and the breaker points closed.

Should be 3 Amps or a bit more for a good, hot spark, and not over about 4 Amps to avoid overheating the points and coil.

If significantly over 4 Amps, "adjust" primary resistance to bring it down.

You will see more that run around 4.5 amps than you will see in the 3 amp range. I don't think I have ever seen a front mount 12V coil with the OEM resister run lower than 4 amps. Every ft. mt 12V coil I have checked are 2.5 ohms and a few 2.4 I have never seen one lower. That's just my observation, 4.5 amps is not a deal killer : ) BTW my test equipment is top of the line not HF junk.

For those in the new an out of range ohm meter value can tell you its bad but a ohm meter value in range cannot confirm its good.
It can ohm check good but still be bad.

 

[skyking]

Finally got back to checking out this 8N. Plan was to start it up and let it run till it quit. Well that didn't take long, started right up and ran maybe 1 minute and died like I shut the key off and would not restart. I was ready with an adjustable spark tester. Bright blue spark jumped about a 1/2" gap on all 4 plug wires. Good fuel flow at the line going into the carb but next to nothing at the plug on the bowl. Looking like a carb problem. Seems strange to me. I've run out of gas before and they always seemed to gasp before they finally died but not this time. Was like I shut off the ignition switch, running great then died.

 

[used red MN]

Finally got back to checking out this 8N. Plan was to start it up and let it run till it quit. Well that didn't take long, started right up and ran maybe 1 minute and died like I shut the key off and would not restart. I was ready with an adjustable spark tester. Bright blue spark jumped about a 1/2" gap on all 4 plug wires. Good fuel flow at the line going into the carb but next to nothing at the plug on the bowl. Looking like a carb problem. Seems strange to me. I've run out of gas before and they always seemed to gasp before they finally died but not this time. Was like I shut off the ignition switch, running great then died.

There is a screen in the fitting that screws into the carb that the fuel line connects to. Pull the fitting out and clean it.

 

[will-max dairy]

Finally got back to checking out this 8N. Plan was to start it up and let it run till it quit. Well that didn't take long, started right up and ran maybe 1 minute and died like I shut the key off and would not restart. I was ready with an adjustable spark tester. Bright blue spark jumped about a 1/2" gap on all 4 plug wires. Good fuel flow at the line going into the carb but next to nothing at the plug on the bowl. Looking like a carb problem. Seems strange to me. I've run out of gas before and they always seemed to gasp before they finally died but not this time. Was like I shut off the ignition switch, running great then died.

If you look at the carburetors on these old tractors, many of them will have dings in the bowls, where people smacked them with a screwdriver (or whatever) to get a sticky float to drop.

The people that I grew up with, if they experienced the problem that you are, they would whack the carburetor a couple of times to see if the
"float was sticky"... in this case, stuck in the up position...

Sometimes they got a little overzealous.

And then, if that didn't work, they would look at the screen, or remove the carburetor for inspection/cleaning.

 

[will-max dairy]

Starters often have the same dings...

 

[skyking]

Cold, windy and wet here today. Guess that made the decision to work on the 8N easier. First checked the gas tank and according to my calibrated dip stick there was 3 gallons of fuel in the tank. Removed the gas line at the carb and a good steady stream. Re-attached the line and removed the plug on the bottom of the carb bowl... just a dribble. Nothing changed from the other day,,, a guy can wish. Shut the fuel off and removed the gas line at the carb and the elbow. Could not believe that it was that dirty. I just cleaned this about 2 hours run time ago when I installed a new fuel shut off valve. Cleaned the screen and reinstalled everything. Ran it in the shop at various rpm for 20 minutes with out a hiccup. Guess that was the problem all along. Just want to say thank you to everyone for your assistance.

 

[Eman85]

Did the old shutoff valve have a screen that went into the tank? Did the fuel bowl have a screen in it? The screen in the inlet is the 3rd inline filter.

 

[used red MN]

Could not believe that it was that dirty. I just cleaned this about 2 hours run time ago when I installed a new fuel shut off valve.

Same as Eman is saying, if the shut off you added is just a valve you should either go back to the sediment bowl type that has a screen in the top or add an inline filter that is a STRAINER SCREEN type. Paper element type filters can sometimes be to restrictive for gravity flow systems. That fine screen in the carb inlet is only supposed to be a safe guard against dirt or crud passing into the float needle and causing it not to seal. Example of a strainer filter.m

 

[skyking]

It is a sediment bowl, I just couldn't think of that name and fuel shut off was the first thing that came to me. Sucks getting old, the old memory isn't what it was. Yes there is a screen in the tank. It is not as fine as the other two almost like the screen in your house windows. What was in the carb inlet screen was like silt, really fine but like a paste if that makes sense.