8N Wiring Questions

[Beanmedic]

New tractor owner (old tractor). Best I can determine I have a 1950 8N with side mount and 12 volt conversion with alternator.

When I picked it up it didn't miss, but did when I got it home. So I suspected spark first. It has improved with cleaning and regaping points and new plugs. Wiring was iffy, with electric tape splices. So I dedided to clean and repair and also improve the ign system. Installed the EI and 3 ohm flamethrower coil. As I move through the wiring repairs I have a couple of questions.

The EI works well and the tractor cranks and runs much better than before. I notice that the "square" resister is in the circuit. Looking at the EI instructions I can see how folks become confused. First says to leave in the resister if it is presently in the circuit. Reading on you find that the chart suggests no resister if you have a 3 ohm coil. So the initial instruction to leave it must assume you are leaving in the old coil. But with a 3 ohm coil (flamethrower) I should have resistance built in the coil. So, is there any advantage in the external resister also being in the circuit? I'm thinking not.

Secondly, I note that the alternator has only one wire from the BAT post to the battery. Seems to me that without the feedback circuit wired that the alternator is being used as not much more than a glorified generator. Is that correct?

 

[Dell (WA)]

David.......REMEMBER, the 1-wire alternator requires goosing the cold engine to about 1800rpms (3/4-throttle) before it starts charging. After internally turning on, it will charge at 600rpms like the 3-wire. It's MODIFIED internal voltage regulator semi-keeps the VOLTAGE to about 14.7-volts (can go as high as 17v? without regulation) 14.7v will keep yer 12-volt battery nicely charged but should NOT boil the battery. Its a DIFFERENT regulator scheme than the 3-wire feedback scheme.

Ah resistors.....mysterious devices that bedevil novice shadetree mechanics. BEFORE yer conversion to EI, the previous converter used the cheap'n'dirty scheme of using the original 6-volt roundcan coil AND a 12-to-6v converting resistor. Since you used the recommended EI 12v "Flamethrower coil" which is designed to NOT use a resistor as required for the original 6v coil.
THEREFORE, you DO NOT NEED enny resistor with yer 12v FlameThrower coil. UNDERSTAND???

I sure wish Pertronix would re-write their AWFUL instruction sheet.

Realize, with the "FlameThrower" coil, you will have HOTTER sparkies (more kilovolts) and you need GOOD silicon soft and flexible copper-core sparkie wire. ($15, cheap) Do not use modern anti-radiostatic carbon-string sparkie wire.

Yers is one of the SUCCESSFUL 12v Electronic Conversions ...because... its the 5-nipple sidemount which has ROOM for the EI module. Congratulations. .......Dell, yer self-appointed sparkie-meister and 12v advocate for the right reasons

 

[NOXJohn]

I have a 1949 front mount distributor that I converted to a 12 volt system and electronic ignition. I used the same 12 volt flamethrower round coil. I called the electronic ignition manufacturer before I started it up because I was afraid the 3 ohm coil would allow to much current to flow through the E/I system and burn it up. The guy I talked to was very knowledgeable about their product and 8N's. He said the flame thrower coil would be OK without a resister. I have about 25 hours on the new system and no problems. The tractor runs better then it has in the 22 years I have owned it. You should call the manufacturer to make sure but I think you are OK.

 

[souNdguy]

as Dell said.. no, the 1-wire alt is not in any way like a generator, other than it makes electrons move..

It simply has an internal voltage regulator.. the downside, as mentioned, is it likely takes high rpm to start her charging.

if I were you, I'd investigate seeing if it would run as 3 wire.. if so, run a wire from #2 on the spade plug to the bat stud, and then from the #1 connection thru a 194 lamp or similar, to the switched side of your key switch.

post back what you find.

you can use a volt meter to see when the alt kicks on.. IE.. start her up and raise rpm till voltage goes up, then go 3 wire and see if voltage goes up at a lower rpm.

soundguy

 

[Mikey's 8n]

I have the same set up on my 51 8N. Converted to 12 volts, EI, and Flame thrower coil a few years ago....Best thing I ever did for the old girl !!!
No resistor is needed... And my single wire alternator starts charging as soon as I stsrt it up....no need to rev it way up.

 

[Beanmedic]

WOW! Thanks guys! Great information. Oh, having a little electronics background I knew to get rid of the resister "carbon and string" spark plug wires. What was surprising to me was that the seller had just had a tractor dealer check her out and put those lousy spark plug wires on the system. And thanks to the forum I installed a hotter plug with the new spark plug wires and EI system.

Can't wait to test the single wire and three wire differences. This tractor does not have a proofmeter so I'll get the rest of the wires replaced and pick up a digital tach for accurate readings. I'll post back when I can get that done.

Y'all ROCK!

PS: I replaced the 10 weight motor oil with a 30 weight to get the oil pressure up. Everything was running so good this weekend that I did my first bush hogin' after reading all the safety advise I could find. Worked great thanks to all you forum advisors.