8N front mount resistor help for electrically challenged

I am struggling getting my front mount 8N running right. I switched to a 12 volt system about a year ago mainly because I could never get the 6 volt charging system running( I tested the generator, polarized and switched regulators). So the tractor kept dying and I was constantly charging and frying batteries.

So anyway, got all new wiring, alternator working and tractor firing I kept the original OEM resistor but did not add the secondary resistor because when I put in the secondary, it would not fire.

So you know the story. I've fried a couple square coils and I fried the OEM resistor.

The secondary resistor that came with my 12V kit is 6ohms which is too much.

At this point, I have a new coil with 2.5 Ohms, an OEM resistor which shows no resistance because it is not hot. I fired it up just to hear it run, and ran like a champ. Turned it off immediately.

My problem is this. I have read several threads about ohms law and testing procedures it is beyond me. I am older, stupid and my meters are not reliable on the ohms scale.

So my approach, is to add a second resistor that will give me the most resistance to protect the coil and let the tractor run. The 6ohm resistor is TOO much. I was going to buy a 4ohm, 3 ohm and a 2 ohm resistor. Try the 4ohm first and if it works I am done. If not, then drop to the 3ohm and then the 2ohm if needed to make it fire.

I do not know where to buy the resistors and when I have looked on ebay, the resistors also talk about Watts. I do not understand electrical so I don't get it.

Where can I buy the resistors I need and what wattage should they be if it matters?

Thank you,

Electrically challenged Obie

if your heart is set on replacing it, just try a 2 ohm resistor. congratulations, btw - at 6 ohms, the resistor that came in your kit is the new record holder. the highest i can remember reading about before this was 5.5 ohms.

but i had the same issue - my resistor would not let the tractor fire, so i removed it. it was 3.5 ohms. i've been running without that extra resistor in my system since then. i am now in my eighth year of running it like this. i figure about 25 hours a year, maybe 30. i haven't fried that 6 volt coil yet.

Would you know how many watts the resistor should be?

Don't over think this, as people have been thru this hundreds of times. IF you NEVER leave ignition ON with a stalled engine, even 12v and 6v coil and OEM 12250 resistor would survive. Your new 2.5 Ohm 12v coil and OEM resistor will be just fine with nothing extra, BUT even it will fail if you walk away with ignition ON with stalled engine. If you MUST play with resistance, I say the 4, 3, 2 Ohms are all too large. IF you MUST, try about 1 Ohm or less at about 10 to 20 Watts......but I would skip the resistance play and go with 12250 & 2.5 Ohm coil.

OK. Thank you.

Why do the 12v conversion kits send a second resistor? Is that to protect the 6 volt coil?

(quoted from post at 11:08:43 06/15/19) OK. Thank you.

Why do the 12v conversion kits send a second resistor? Is that to protect the 6 volt coil?

Click to expand...

es, but as has been said, the values of what they send make it all but useless, because even with the same part number, the resistance values run all over the map.

Might want to scrap you old VOM and get a new meter. Using inaccurate test equipment is like changing spark plugs with a pipe wrench. Your results will be mixed and questionable at best.

(quoted from post at 10:46:27 06/15/19) Might want to scrap you old VOM and get a new meter. Using inaccurate test equipment is like changing spark plugs with a pipe wrench. Your results will be mixed and questionable at best.

Click to expand...

Why would you assume his old VOM is not accurate? I would rather use my 40 year analog VOM over any new jumk!

(quoted from post at 12:08:43 06/15/19)

Why do the 12v conversion kits send a second resistor? Is that to protect the 6 volt coil?

Click to expand...

i sometimes wonder if it's just another practical joke from the same people who brought us the so-called reserve pickup on the sediment bowl.

calculator at bottom of page.

http://www.m0zpk.co.uk/ohms-law-equations-and-triangle/