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8N OEM Ballast Block

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2Czech

07-25-2007 08:57:46




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Just did a 12v conversion (for right reasons) using a kit & 1-wire alt. Had to modify the &^%$&# mounting bracket to make it fit but got it done. Kit came with a coil marked 12v but ohmmeter check read like a 6v (1.2 ohms). Ran for an hour then died. Bench tested the coil and it was bad. Replaced w a 2.5 ohm 12v coil, ran fine for about an hour died. This time it was the &^%$* aftermarket points (cam follower). Installed used Ford points, running again.

Here"s where it gets interesting. Upon further testing found that with nothing connected to terminal on the ballast mounting block I had 6v present. Turns out the old block itself was conducting. Replaced it this morning, brother-in-law will be testing it shortly.

BTW this is a great and very helpful forum.

Joe

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2Czech

07-26-2007 06:36:49




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 Re: 8N OEM Ballast Block - Update II in reply to 2Czech, 07-25-2007 08:57:46  
Well my brother-in-law (who gave up some of his vaction to help me get the 8N converted) ran the tractor all afternoon yesterday so I think its safe to say we got the bugs worked out.

Once again thanks to everyone that contributes accurate repair information to this forum. I was able to find the answer to every question I had.

Its great to have the 8N back in service.

Joe



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2Czech

07-25-2007 13:35:46




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 Re: 8N OEM Ballast Block - Update in reply to 2Czech, 07-25-2007 08:57:46  
Well my brother-in-law reports it again ran for a short period then started missing & backfiring. He discovered the spring tab on high voltage side of the coil was bent improperly not making contact with the carbon post on the dist. cap. Just got a report from my sister apparently its running and he's a shreddin'. I hope we can call it fixed.

Joe



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don b

07-25-2007 13:00:30




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 Re: 8N OEM Ballast Block in reply to 2Czech, 07-25-2007 08:57:46  
Joe....you better check your new terminal block resistor too,or you may be replacing the coil again.The new resistor should measure about .5 ohms cold and about 1.5 ohms hot.While your system with the 2.5 ohm coil and the 1.5 resistor will work, [14.2 volts divided by 4 ohms =3.3 amps]the addition of one of Dell's trick resistors[.5 ohm] would probably help your points life.IMHO don b



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2Czech

07-25-2007 13:41:26




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 Re: 8N OEM Ballast Block in reply to don b, 07-25-2007 13:00:30  
Thanks for your input. I did check the new one and if my not so good memory serves me it read .6 ohms cold. I also have the 1 ohm resistor that came with the kit in series with the coil and OEM ballast so I think I should be in good shape. Thanks--Joe



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don b

07-26-2007 06:27:30




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 Re: 8N OEM Ballast Block in reply to 2Czech, 07-25-2007 13:41:26  
Joe....did you have the one ohm resistor and ballast resistor in line when you installed the previous 1.2 ohm coil? I believe you have a little too much resistance in the system now.Should result in weak sparkies and hard starting. don b



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2Czech

07-26-2007 06:47:23




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 Re: 8N OEM Ballast Block in reply to don b, 07-26-2007 06:27:30  
Hi Don,
I did have the 1 ohm kit resistor in line with the coil that came with the kit so I was surprised when it failed. I had the same thought about too much resistance and built one of Dell's .5 ohm resistors but went with the kit resistor and the new coil initially out of caution. I think now I'll switch over to the .5 ohm see how it does. Or should I just leave well enough alone?

Joe

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don b

07-26-2007 08:46:43




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 Re: 8N OEM Ballast Block in reply to 2Czech, 07-26-2007 06:47:23  
Joe.....did you check the resistance of the 1 ohm resistor?Did you check the ballst resistor hot?What is your voltage reading at the coil now?Should be about 9-10 volts.
If you had the 1.5 ohm ballast and the additional 1 ohm fixed resistor,plus the 1.2 ohm coil,that's 3.7 ohms divided into 14.2 volts =3.8 amps.This a little high,but I'm surprised it burned up your coil. don b



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2Czech

07-26-2007 10:26:24




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 Re: 8N OEM Ballast Block in reply to don b, 07-26-2007 08:46:43  
Don,
I did check the 1 ohm kit resistor and it measured 1 ohm. I did not check the resistance of the OEM ballast hot. As memory serves me the voltage check initially (w kit coil) was around 9.5v. The primary of the failed coil still reads 1.2 ohms but when tested it doesn't produce a spark on the HV side.

I'll need to re-measure everything now to see what my readings are. Last report from my brother-in-law is that after successfully running it all afternoon yesterday now it starts and runs but backfires and has poor power. He's heading back to San Angelo today and I won't have time to check it until the weekend (if it ever stops raining).

I really appreciate your help.

Joe

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don b

07-26-2007 11:32:54




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 Re: 8N OEM Ballast Block in reply to 2Czech, 07-26-2007 10:26:24  
Joe....sounds like you know how to hook up the 12v system without me.I still have not figured out why your first coil went south or why you had voltage at the terminal block with no wires connected to it.Where was it coming from?Also I would check the rotor button on your backfire problem.Sounds like it may be cracked or worn.BTW...Send us a little of that rain. don b



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2Czech

07-26-2007 12:51:44




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 Re: 8N OEM Ballast Block in reply to don b, 07-26-2007 11:32:54  
Hey Don,
I've got a background in electronics so the theory of how this ignition is supposed to work and how to connect the parts all makes sense but it was very interesting to learn the specifics regarding the proper current flow and the behavior of the OEM ballast.

Regarding the coil that failed I'm not sure what happened to it. Perhaps the insulation broke down internally or something. I was dinking with it the other night and it fired a couple of times so maybe something is loose inside. I may try resoldering the spring on the HV side. As far as the voltage present on the terminal on the old ballast block, that block was made of layers of insulation material pressed and glued together to make a thick block. The layers have separated some and the whole thing is really dry and absorbant. All I can figure is perhaps it was sprayed with something that conducts electric current and it soaked into the material. Its definately gone from an insulator to a conductor some how. This is probably what was draining my battery.

I'm not sure where you are but here in S Central Texas we have had record rainfall this year. The corn and maize will probably rot in the fields.

I'll check the rotor. The one that came with the tune up kit was made wrong so we recycled the old one. Some of the aftermarket 8N parts just "ain't" made right.

I'll let you know what I find. Joe

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2Czech

07-27-2007 06:55:04




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 Re: 8N OEM Ballast Block in reply to 2Czech, 07-26-2007 12:51:44  
Don, I thought you might find this interesting. I re-tested the kit coil on the bench only this time I installed it in my spare distributor and with one spark plug connected. It fired the plug consistently with a good blue spark. I think the big difference in my 2 tests was the absence of the condenser in my 1st test. Now I'm really scratchin' my head wondering what killed the spark the first time because the plugs definately weren't firing. It sure leans toward a condenser problem. I'll need to do some more pokin' and proddin'. This is really bugging me now. Joe

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