6 volt coil question

[DJ54]

12V test light will work, will just be dimmer. I use mine on all of my tractors 6V & 12V both.

 

[rScotty]

I use automotive coils interchangeably. A good one is good for decades. All that matters seems to be the voltage. Polarity doesn't matter to any coil I've used. My JD is 12 volt positive ground, so any 12 volt coil works. To test it I just lay a spark plug on the engine block, hook up the wires, and interrupt the low voltage points wire.
I have found that the spark plug cable is often a culprit in weak spark. Now I use copper stranded core spark plug cable -Belden brand wire with neopreme plug & coil ends that I got at a vintage auto show.

 

[wolc123]

This sure has been an old fashioned winter, here in the north west corner, of NY state. Not sure what happened to global warming ? For the first time, since my Farmall Cub quit running in January, it’s warm enough on a weekend to work on my broken down “off-brand”tractors out in my unheated barn.

Even though I will
likely “need” my Ford 8n before the Farmall, I’m going to start with the Farmall because it’s likely to be the quicker fix. The “brilliant” engineers at Ford, designed it so that the hood and gas tank need to be removed to work on the coil.

I really don’t need either one of them since my grandpa was wise enough to replace his team of horses with John Deere tractors, as the primary power on our farm, back in 1950. I’ve always had a green tractor available to get the work done when it really needs doing.

If I can’t get the Farmall going today, I’m going to winch it onto a trailer and drop it off at our local, semi-retired Farmall mechanic’s shop. He got it running real good for me a few years ago, after it had sat unused in a factory building, for about 20 years. He loves working on Cubs. I’m still working full time and then some at my factory job, so I may not have the free time that it takes to get this one, and my old Ford, running good again.

 

[wolc123]

Sounds like more of an electrical connection problem being that it died that quick. A simple test light will help you diagnose that problem. Put the clip end on a good ground, battery is best if the lead is long enough. Put the tester end on the input side of coil from switch, it should light up with switch in the run position. If you show voltage there, with tractor in neutral, put tester on the output side, and roll the engine over with the starter. Test light should flash. If it flashes, put the tester on the connection point on the distributor and turn over, you should see it flash. Doing that, you know your wiring is good to there. Remove the distributor cap and check the connection inside, you should still see if flashing when turning over. I have seen those Bakelite insulators crack, and short out on the distributor case.

If you have voltage to there, turn the switch off for a moment. Rotate engine until points touch. Turn switch on, and break/separate the points manually with a small screwdriver, you should see a small spark when the points separate. If you see a spark, look closely at the points, especially the rub block. The lesser expensive contact points set's rub blocks can wear, bend, or completely come off. The one on my TO35 Ferguson was completely gone. Friends of mine literally gave me this tractor and several attachments just to get it out of their yard. They got frustrated after piddling with it, and just wanted it gone. A new points & condenser kit, new plugs, purged/cleaned the fuel system, and a good carb cleaning, and it fired right up. A few more issues to deal with when I get time but should be a good useable tractor once time allows to look into those.

If you have voltage to inside the distributor, I'd have to guess it's the condenser. Some simple diagnostics like this can save you a lot of money just throwing parts at it.

If it does look like the condenser is the issue after this diagnostic test, do you think a spare condenser from my Ford 8n would work on the Farmall cub ? Both tractors are similar vintage positive ground 6 volt with 4 cylinder engines.

I’m hoping that’s the case, because I have several of those in my parts cabinet. It’s going to be tough and/or expensive to get a “proper” coil on that Farmall, if the coil turns out to be the issue.

 

[DJ54]

Battery ignition systems usually use a condenser rated .20 to .28 microfarads, so you should be OK if you can get it stuffed in there.

 

[wolc123]

Battery ignition systems usually use a condenser rated .20 to .28 microfarads, so you should be OK if you can get it stuffed in there.

No luck with it today. Now I have about 3 hours into it plus the $34 NAPA coil, so I’ve reached my limit on time and parts for the “do it myself” attempt.

I’m going to give my Farnall mechanic buddy a call and see if he’ll let me borrow his trailer and if he has time to work on it. If you so, I’ll winch it on his trailer, and haul it over to his place. I’m in no hurry for it, and it will be nice to free up the barn space here.

While he has it, I’ll get him to do an oil and filter change and lubricate the throw out bearing. That’s a pain to get at. Hopefully, I’ll get another 2 or 3 trouble free years out of it, after that.

I did manage to make a new bracket for it to take the standard NAPA 6 volt coil. I’ll keep the OEM one, in case my buddy wants to put that one back on it, or if I ever blow the NAPA one.

My diagnostic check showed power to the input side of the coil, with the switch on run, but the test light did not flash on the output side. It glowed steady but dimmer than it did on the input side. That’s why I decided to try the new coil. Still no go though.

Next, I’ll take the snowplow, drawbar weight, and rear tire chains off of the Cub, and get it ready to trailer away. After that, I’ll start working on the old Ford. Hopefully, a NAPA coil will do the trick on that one.

My dad gave me his old Shopsmith last fall and it worked pretty good, with an end mill, to make the new coil bracket base from a piece of brass. I’ve never been much of a woodworker, but I used to use it a lot when I was living at home as a kid, for various metal projects.