Replacing a coil on an 8N

[slapshot]

I am replacing my coil on my '51 8n.
The coil that is currently on it has two wires labeled DIST and BAT.
My new coil is labeled simply "+" & "-"
This is a 12v negative ground tractor, so I assume that the DIST = "-" and BAT= "+"
Does this ssound correct? What would happen if I wired it backward?

Thanks
-dave

 

[Soundguy]

Loss os spark intensity.. though it wold work.

Old coil was dist / bat.. since it was positive ground. that meant bat HAD been hooked to negative.. which was the 'hot' post.. and distrib HAD been hooked to positive. which was the ground plane.

On your new coil.. simply match the polarities.. Hook the (-) to negative.. which in your case is the ground plane.. hook (+) to positive.. which is from your ignition switch.

I hope you are using a real native 12v coil.. like a NAPA IC14SB (15$ ).. and not an oem style 6v coil AND a dropping resistor ( 8NE10306 ). You'll get better performance out of the true 12v coil and no resistor vs the older style 6v coil and a resistor as wear and corrosion set in to the electrical contacts.

You can also play with larger than normal spark plug gaps to get a hair more KV potential out of the spark before it jumps.... that helps with fouling.

BTW.. points gap is .025 on the sidemount.. and so is spark plug gap.. though if using all 12v stuff including a coil.. I'd be inclined to use .028 spark plug gap or so.

Also.. OEM spark plugs were a ch H10.. it's best to go one range hotter and use H12.. or more preferably.. Autolite 437's ( could also use NGK 3112 )

Use a metal core wire.. TSC sells it in a cut-to-fit kit. Modern resistor core carbon composite wires don't due the anemic ignition system justice... besides the spark gap a tthe points will be throwing off enough emi/rfi that having supressor wires won't do ya any good.. even if ya got a radio..

Soundguy

 

[AMP762]

I know you have more old Ford smarts than me,but are you saying to run 12v to the coil.If so doesn't that eat points?

 

[slapshot]

Thanksfor the help....I love this site.
I got everything put back together last night. Now my sediment bowl is leaking, but that should be an easy fix.

-dave

 

[Soundguy]

I know you have more old Ford smarts than me,but are you saying to run 12v to the coil.If so doesn't that eat points?

Did you miss this sentence in my post:

I hope you are using a real native 12v coil.. like a NAPA IC14SB (15$ ).. and not an oem style 6v coil AND a dropping resistor ( 8NE10306 ). You'll get better performance out of the true 12v coil and no resistor vs the older style 6v coil and a resistor as wear and corrosion set in to the electrical contacts.

"eating" points as you mention is usually due to coil primary current being too high. This is usually due to coil primary resistance being too low. this is usually due to running a 6v coil on 12v. As i mentioned in my previous message....Your (2 soloutions) are to:

1, use the appropriate dropping resistor inline with the 6v coil. An 8NE10306 is the favored dropping resistor of choice in ths application. With this resistor in series, after the key switch, befor ethe coil primary, the total serial primary resistance will be sufficient to protect the points.

2, cut out the middle man.. simple use a REAL native 12v coil that has a primary resistance sufficient to ensure long coil and breaker lift.. 3.0 to 3.5 ohms is normal.. with 3.0 to 3.2 ohm being closer to ideal, imho.


Soundguy

 

[Soundguy]

Thanksfor the help....I love this site.
I got everything put back together last night. Now my sediment bowl is leaking, but that should be an easy fix.

-dave

The cork gaskets for the sed bowls are worse than cr@p.. Make one out of thick gasket paper.. or use a napa neophrene 50cent fuel bowl gasket, .. balkamp part number 730-9506. save yourself some trouble...

Soundguy

 

[AndyM]

Chris,
The Delco-Remy coil I removed has a + from the distributor and - from the battery. (I'm assuming this was the original 6 volt positive ground coil?)
I plan on going to NAPA tomorrow to pick up a NAPA IC14SB coil. Do you know off hand how they are labeled? (+/- or BATT/DIST)
Even though the coil I took off has the "-" coming from the battery, I assume the new coil will need the "+" coming from the battery.

P.S. It's been a long time since I've posted here... how the heck have you been? You probably have 20 more tractors since the last time I checked!

 

[AndyM]

I think I figured it out but additional feedback is welcome...

My guess is the Delco-Remy coil is original to the 6 volt system, which is probably why the "-" terminal on the coil goes to the battery. If NAPA is open tomorrow (Memorial Day), I'm going to assume the 12 volt IC14SB coil gets hooked up with the "+" going to the battery.

My poor 8N has been neglected for a couple of years and I'm going to give it some attention... then one of the tractors will need to go. (preferably the NH, but we'll see how things go)

 

[Soundguy]

I think I figured it out but additional feedback is welcome...

My guess is the Delco-Remy coil is original to the 6 volt system, which is probably why the "-" terminal on the coil goes to the battery. If NAPA is open tomorrow (Memorial Day), I'm going to assume the 12 volt IC14SB coil gets hooked up with the "+" going to the battery.

My poor 8N has been neglected for a couple of years and I'm going to give it some attention... then one of the tractors will need to go. (preferably the NH, but we'll see how things go)

I can assure you there were no delco-remy coils on the 8n's when they rolled out of the factory.

Always orient a coil based on battery polarity.

if you are negative ground, then negative to points.

if you are positive ground, positive to points.

if the coil is marked bat/distrib, and you know the original orientation of the tractors electrical system when it left the factory.. then go from there.. if they were positive ground.. like a ford N.. then the original coils' 'bat' will be negative,, and the 'distrib' will be positive.

ic14sb are labeled +/-

soundguy