No Spark to plugs...please read and help

[Jerry/MT]

It's supposed to more than just a horshoe shape. It has a vertical projection also. The part number is 8N122143. The rotor part number is C0NN12200A. The cap part number is NCA 12106A and the dust cover is FAA12239A.

 

[Soundguy]

ps.. what kinda coil you got. to my knowledge nobody currently makes an 'internal resistor' coil. there are coils that are native 12v and do not require external series resistance though.. napa ic14sb is one example.

ditto no checking advance mechanism...

 

[Soundguy]

and I've found some new caps don't fit with the dust cover.. and old caps dont fit without it. some combination may be causing no contact to the rotor. if it sparks coil 2ndary to block.. but not thru rotor.. then perhaps cracked rotor or ill fit.. or bad advance..

 

[ruffdog]

Instead of having to crank your tractor everytime to check for spark, disconnect your neg points wire from coil and just use a jumper wire to ground. Just make sure your rotor is lined up to one of your plug wires and touch and release your jumper to act as your points. I also have seen rotors leak to the dist shaft.

 

[Guesseral]

I just did the same thing to my tractor, and had bacicly the same problem. First the dust cover and cap (as stated previously) did not allow propper alignment and I had to toss the new dust cover and use the old one. Next the tractor would start and stall after a while and then start after a while and stall again then start and run good but do the same thing all over again, this took some research but here is what was wrong. The new points were shorted out and I was getting a constant positive and negative to the coil no arcing from the coil. I had also changed the wire from the insulated post through the distributor to the points and the insulated post was now intermittantly shorting to the distributor same problem. I spent a lot of time tracing this system out, it's really discuraging that it took so long because the operation is so simple.
But that doesn't seem to be your problem because if you can get spark directly from the coil (thats a good idea I never thought of) then the only problem would be from the cap to the plugs. So it has to be between the coil wire through rotor through the cap through the plug wire. I would have to lean twords the cap and rotor not making propper contact which could be the cap not propperly seating on the dust cover. Yea I know pretty generic of an answer.

 

[nj82tj]

Thanks all for the replies. I might try a new dust cover. I have a new cap but old cover. If that doesn't work I will end up pulling the entire distributor out and going over it. The coil by the way is a NAPA coil, 12volt with internal resistor. I'll be sure to post more if-when I find anything out.

 

[Soundguy]

i know of no comercially made napa coils that ACTUALLY contain an internal resistive element.

post the coil number.

If it is a napa coil MADE for 12v native use.. it's primary winding will contain the correct number of turns of wire of the correct diameter to produce correct primary circuit resistance ( usually in the 3-3.5 ohm range )

IMHO.. I'd not pull the dizzy. next thing I'd check is the feed thru insulator.. and then the breaker plate..

 

[ruffdog]

Was baling straw with the neighbor today with his Allis WD tractor. The same thing is happening with that tractor. Was running great and it was like the switch was turned off. Over the winter, he too installed a one wire alternator and went from 8v to 12v system. Just like the op, we have spark out of the coil wire but is not getting through the cap to the plugs. While I was checking his tractor, I saw he had a 6v coil and it was sparking at least 1/2". One thing I am wondering: When he upgraded the electrics, is the ignition system getting excess voltage and is overpowering the cap/rotor with such a hot spark? Maybe we will have to install a resistor to drop it back some.

 

[Soundguy]

you might want to read up on electrical theory first before you start doing stuff.

sparkpotential is defined by atmospheric pressure, makeup, and spark gap.

if you have a plug gapped at .02 and another at .03 the one at .03 will require more KV to jump the spark gap. all other things equal, the spark will always jump at the minimum KV needed.

thus.. adding 'hot coils' and whatnot does not increase spark potential at the plug unless GAP is changed.. I love reading hotrod mags and seeing them tell peopl they will get a hotter spark changing to this coil or that coil.. yet not tellignthem to increase spark plug gap.. etc.

primary current is what you arecontrolling when you add a resistor. primary curent will need to be controlled to make sure the coil can disipate heat ( wattage determines this ).. and to keep points happy. points surface area determines what amperage they can conduct and their design dictates how much wattage ( heat 0 they can disipate. you will sometimes se ventilated or peirced points.. etc. ( dwell or duty cycle effects all this ).

most points like about 3.5a on average primary current.

oil potted coils disipate heat better than epoxy or tar potted coils, or solid coils.

condensor is just a switch debouncer.. points are just a switch. condensor provides a path for current flow at the moment the points open to prevent arcing and burning.. oncve points open far enough so that no arcing is present, the condensor has done it's job.. it's just a quick stopgap.. without a condensor ( open ).. the points would pit and burn quickly.

 

[Ford851]

When you say you can use any wire from the cap and plug it to the coil and get a very nice blue/ white hot spark. Do mean you take one of the plug wires(1 of 4) and plug the spark plug wire into the center plug hole on the coil and it sparks when you hold the other end of the plug wire close to the tractor body (ground). If so, I would say your problem is in the distributor to the plugs.

Or two, do you mean the spark plug wire is in one of the outside holes on the distributor cap and you spark at the frame of the tractor?

It sounds like the secondary current coming into the center of the distributor cap is not being transferred to the outer ring of spark plug holes. The dist. cap could be cracked, the tang on the rotor is not touching the center hole inside the distributor cap, the rotor is bad, or the shaft on the distributor is sheared off and is not fully spinning around.
I'm assuming that you have set up your timing properly and the distributor has not slipped. I have had this problem before myself. I had to slowly turn the distributor, lock it down, move it again until I got it right.

If you think its timing, post back and I'll help you.