8n no spark (another thread)

[2mnhawbs]

Greetings, hopefully I am posting in the right subforum and apologize if I am not.

I am seeking help on my 48 8n tractor that I am in the process of mildly restoring.

My issue is no spark. I recently converted to 12 volts, replaced the points, condenser, rotor, crab cap, coil, entire harness, and probably something else I am missing. I have voltage at the coil, but no spark from the plugs (I removed a plug really connected the wire and turned it over but nothing). The points are gapped at 15 thou, and not grounded when open. I tried switching the old coil, and the old condenser. Hopefully i havent left anything out. I am starting to get frustrated and do not know where to turn, I have researched **** near every thread about 8n electrical problems and ruled out a lot of things. SOMEONE PLEASE HELP AN ENTHUSIASTIC YOUNG GUY GET IS 8N GOING. THANK YOU IN ADVANCE TO EVERYONE.

 

[pmsmechanic]

Are your points open too wide? If they don't close there will be no spark. Also take the center wire out of the distributor and put a spark plug on it. If you have spark there but not at the spark plug wires then there is a problem in the distributor.

 

[2mnhawbs]

Are your points open too wide? If they don't close there will be no spark. Also take the center wire out of the distributor and put a spark plug on it. If you have spark there but not at the spark plug wires then there is a problem in the distributor.

They are set at 0.015

 

[pmsmechanic]

They are set at 0.015

Yes but if the distributor cam is worn they won't close enough to make an electrical connection. There should be a bit of a spark at the points when you open and close them manually.

Take the distributor cap off and turn the engine over until the points are closed. Take the center wire out of the distributor cap and either hold it close to the block or put a spark plug into it. Lay the plug on the engine where you can see it. Turn the key on and take a small screw driver and open and close the points with the screwdriver. There should be a small spark at the point and a healthy spark at the spark plug. If there is no spark at all then your points are set too wide and they are not closing which is what they need to do in order for there to be spark.

 

[calman93611]

Hopefully you have your old rotor. Pull off the new and compare with the old. The gap between the rotor and the distributor cap have to be fairly precise. If it is too large then it cannot bridge the gap. Also check the points and make sure that the points where the condenser attaches has the insulator piece in place or condenser will ground out. I know this is a stupid point, but make sure that the distributor cap is in the correct place, should be notched where it seats on the distributor.

 

[LD1]

IF you have no spark at the plugs, step one should always be to see if you have spark at the coil wire.

Spark at coil but not at plugs tells you the problem is with the rotor, cap, or plugs/wires themselves

No spark at coil tells you to look at points or the coil setup.

Doing that basically tells what half of the system is bad so you arent messing with good parts. Rotor and cap has do bearing on weather you have spark at the coil.

Since you did a 12v conversion, are you running a 12v coil or a 6v w/resistor?

 

[2mnhawbs]

Hopefully you have your old rotor. Pull off the new and compare with the old. The gap between the rotor and the distributor cap have to be fairly precise. If it is too large then it cannot bridge the gap. Also check the points and make sure that the points where the condenser attaches has the insulator piece in place or condenser will ground out. I know this is a stupid point, but make sure that the distributor cap is in the correct place, should be notched where it seats on the distributor.

I swapped the rotor to the old one to check that.I have checked that the condenser is not grounded, and also the points when they are open. Also made sure that the nipple on the distributor cap is properly seated. Still nothing.

 

[2mnhawbs]

IF you have no spark at the plugs, step one should always be to see if you have spark at the coil wire.

Spark at coil but not at plugs tells you the problem is with the rotor, cap, or plugs/wires themselves

No spark at coil tells you to look at points or the coil setup.

Doing that basically tells what half of the system is bad so you arent messing with good parts. Rotor and cap has do bearing on weather you have spark at the coil.

Since you did a 12v conversion, are you running a 12v coil or a 6v w/resistor?

When I get off work today I will check that I have spark from the coil. I verified that I have 12 volts on the pigtail spring, but have not checked for spark. How exactly should I check to see if it is sparking? Should I hold the coil pigtail wire over bare metal on the block?? I have a 12 volt coil.

 

[Utopia Texas]

I have owned 6 8N tractors and the points were always listed to be set between 20 thousands and 22 thousands.

 

[LD1]

When I get off work today I will check that I have spark from the coil. I verified that I have 12 volts on the pigtail spring, but have not checked for spark. How exactly should I check to see if it is sparking? Should I hold the coil pigtail wire over bare metal on the block?? I have a 12 volt coil.

Not sure what you mean by 12v on the pigtail spring.

You should read 12v on the + side of the coil primary (small wire) when the key is on. Should also read 12v on the - side if the key is on and points are open. It is the act of grounding the - side of the coil through the points that causes the field collaps inside the coil and induced voltage into the secondary side. (spark plug type wire).

If you are getting 12v on the secondary pigtail, the coil is shorted.

To check spark, do as you said. hold the coil secondary pigtail close to the engine block or other ground and crank her over. see if it sparks as a sparkplug would.