Help needed

He guys new on here and pretty much new to working on tractors. My Dad recently passed away and Im trying to get his 1962 IH 340 utility up and running. I replaced the coil with one from Advance not sure if that was right move. Old coil has a batt prong and dist, prong new one just has + - I hooked + side to power wire coming from switch and - side to top mount resistor and out to distributor. Does this seem right? Any help much needed Thanks Pics coming soon.

It will run either way.

-[minus] goes directly to dist.

(quoted from post at 08:32:43 08/04/12) He guys new on here and pretty much new to working on tractors. My Dad recently passed away and Im trying to get his 1962 IH 340 utility up and running. I replaced the coil with one from Advance not sure if that was right move. Old coil has a batt prong and dist, prong new one just has + - I hooked + side to power wire coming from switch and - side to top mount resistor and out to distributor. Does this seem right? Any help much needed Thanks Pics coming soon.

Click to expand...

The power source needs to go to the resistor first, and then to the + post on the coil, and the - post on the coil goes to the distributor.

Yes, it will run the way you did it, but there is a chance of that new coil getting hot and reducing the life of it.

I have to take some "educated guesses" here, so they are that:

1) The tractor is 12 volts Neg ground, right???

2) Since you mentioned "resistor" the tractor
may use a 6 volt coil!!!!!!!!!

3) If you asked for a coil at Advance Auto I
sure wouldnt bet my life its a 6 volt coil

BUTTTTTTTT IF ITS A 12 VOLT TRACTOR AND USES A BALLAST RESISTOR (thats around 1.5 ohms and drops 12 down to 6) YOU REALLY NEED A 6 NOTTTTTTT A 12 VOLT COIL

A coil thats labeled "12 volts for use with (or requires) external ballast resistor is in reality a 6 volt and issssssss the coil you need if its a 12 volt tractor with an external series (between ign switch and coil) voltage dropping (12 to 6). HOWEVER a coil labeled 12 volt orrrrrrrr 12 volts NOT for use with ballast is a 12 volt coil and on a 12 volt tractor YOU DONT USE A BALLAST.

Ifffffff its a 12 volt tractor and ifffffffff it has a series ballast resistor, if you use a 12 volt coil the spark will be weak, YOU NEED A 6 VOLT COIL WHEN THERES A 12/6 BALLAST RESISTOR.

Finally, dont let anyone tell you it dont matter which polarity you wire a coil, its true she will still spark if wired bass ackwards, but its more efficient if wired at the correct polarity. If its a Neg ground tractor, + (Battery) on coil wires to switched ignition circuit (or ballast if used) while - (dist) wires to the distributor. Reverse that for Pos ground.

Get it?? Any questions??? I have to go the fair later so may be away a while.

John T

The more common used way is to wire the ballast between the ign switch and coil input NOT between coil output and distributor, although it can still run as you indicated. I HAVE TO SUGGEST YOU REWIRE AS I INDICATED.

John T

"Finally, dont let anyone tell you it dont matter which polarity you wire a coil, its true she will still spark if wired bass ackwards, but its more efficient if wired at the correct polarity. If its a Neg ground tractor, + (Battery) on coil wires to switched ignition circuit (or ballast if used) while - (dist) wires to the distributor. Reverse that for Pos ground."

You are correct. It WILL RUN with the coil hooked up either way. And a 6v coil WILL RUN on 12 volts without a resistor FOR A WHILE.

Let me guess you replaced the coil because you do not have any spark right???????????? If you answer yes then stop right now and back up and find out what is wrong before buying parts. If you do not have any spark you stand a 95% chance your points are corroded so yep no spark.

For sure, Ive seen many wired backwards and still run (I was a used tractor dealer for years and have about seen it all lol) but data Ive seen shows the coil voltage has to rise as much as 4000 volts higher if wired backwards meaning less efficiency and more heat losses if wired backwards. Its easier to emit electrons from a plugs hotter (electrode) to a relatively cooler (ground strap) is the reason, same reasons why theres a heater under the cathode in an old fashioned radio tubes.

Also right on what can happen if 12 volts is applied to a 6 volt coil (i.e. no ballast), they can get so hot the nasty black oil boils out and/or the coil just has like a melt down.

Fun chat

John T

Wow yes No spark. Thanks

Great thank you John will try that.

On most any engine that has points if it ran when parked but has sat for say 6 months some times less and has no spark it is about 99% of the time the points that have corroded so yep no spark

Ok John I checked and your right it is a 12v coil that says for use with external resistor. As far as tractor goes its a 12v with neg, cable going to frame and pos. going to Im guessing a relay or transformer. I have put the old coil back in place because another response I got was there was little or no spark because points are corroded. This tractor has been sitting for about 5 yrs luckily there was no gas in it to gum any other parts up. Would you also recommend changing point? and do I have reg 12v or neg12v system? Thanks so much truly a big help.

Ok great thats exaclty what happened coil was very
hot after only a few times trying to crank it. Ive
also been told to check my points they are probably
corroded. So I have put old factory coil back on
till I can check my points. Thanks so much!

(quoted from post at 12:40:37 08/04/12) I have to take some "educated guesses" here, so they are that:

1) The tractor is 12 volts Neg ground, right???

2) Since you mentioned "resistor" the tractor
may use a 6 volt coil!!!!!!!!!

3) If you asked for a coil at Advance Auto I
sure wouldnt bet my life its a 6 volt coil

BUTTTTTTTT IF ITS A 12 VOLT TRACTOR AND USES A BALLAST RESISTOR (thats around 1.5 ohms and drops 12 down to 6) YOU REALLY NEED A 6 NOTTTTTTT A 12 VOLT COIL

A coil thats labeled "12 volts for use with (or requires) external ballast resistor is in reality a 6 volt and issssssss the coil you need if its a 12 volt tractor with an external series (between ign switch and coil) voltage dropping (12 to 6). HOWEVER a coil labeled 12 volt orrrrrrrr 12 volts NOT for use with ballast is a 12 volt coil and on a 12 volt tractor YOU DONT USE A BALLAST.

Ifffffff its a 12 volt tractor and ifffffffff it has a series ballast resistor, if you use a 12 volt coil the spark will be weak, YOU NEED A 6 VOLT COIL WHEN THERES A 12/6 BALLAST RESISTOR.

Finally, dont let anyone tell you it dont matter which polarity you wire a coil, its true she will still spark if wired bass ackwards, but its more efficient if wired at the correct polarity. If its a Neg ground tractor, + (Battery) on coil wires to switched ignition circuit (or ballast if used) while - (dist) wires to the distributor. Reverse that for Pos ground.

Get it?? Any questions??? I have to go the fair later so may be away a while.

John T

Click to expand...

Finally, dont let anyone tell you it dont matter which polarity you wire a coil, its true she will still spark if wired bass ackwards, but its more efficient if wired at the correct polarity. If its a Neg ground tractor, + (Battery) on coil wires to switched ignition circuit (or ballast if used) while - (dist) wires to the distributor. Reverse that for Pos ground. "
That's right.......don't let anyone tell you anything unless they can fully explain why. And just connecting + to + and - to - is not going to guarantee you maximum voltage, even though it will yield a negative HV spark, Sir! It depends on the particular coil. If the coil was designed for a Positive ground system & you change it to a Negative ground system & leave coil wired as it was from factory, you get full voltage out, but a Pos polarity spark. Swap the coil wiring & you get your Negative spark, BUT at a lesser voltage, by the amount of voltage across the primary during the spark (typically 100:1 ratio). You can NOT have both neg spark & full voltage UNLESS you swap to a coil with a different winding sense/connection of primary & secondary, as in a coil designed for a Negative ground system. + to
+ and - to - alone will not cut it. This technology is 100 years old & still the information floating around is "what I've always understood/heard" instead of real hard fact. It is just amazing!
Another aspect that really kills the spark polarity aspect is that both the center & side electrodes are cold at start up, just when you need a hot spark the very most.
Further more, your old magneto tractors have every other spark output alternating +/- in polarity, as did all the old HD motorcycles, and many 'wasted spark' modern engines.........so just forget spark polarity, once & for all!!!

Ok John I checked and your right it is a 12v coil that says for use with external resistor.

IF IT SAYS 12 VOLT FOR USE WITH EXTERNAL RESISTOR IT MEANS WHAT IT SAYS AND SINCE YOU HAVE THE RESISTOR, THAT COIL SHOULD BE OKAY

As far as tractor goes its a 12v with neg, cable going to frame and pos. going to Im guessing a relay or transformer.

IF THE NEG CABLE GOES TO FRAME MY GUESS WAS RIGHT ITS A NEG GROUND TRACTOR

I have put the old coil back in place because another response I got was there was little or no spark because points are corroded.

BURNED OR CARBONED UP OR CORRODED POINTS ARE A MAIN CAUSE OF NO SPARK

This tractor has been sitting for about 5 yrs luckily there was no gas in it to gum any other parts up. Would you also recommend changing point? and do I have reg 12v or neg12v system? Thanks so much truly a big help.

YES IF THE POINTS ARE BURNED OR PITTED BADLY OR CARBONED UP ID INSTALL A NEW SET. ITS NEG GROUND SEE ABOVE

SEE MY IGNITION TROUBLESHOOTING


http://www.ytmag.com/cgi-bin/viewit.cgi?bd=farmall&th=5745

John T
John Ts Ignition troubleshooting