No Spark At Plugs

Hello,
Looking for help with a no spark at the plugs issue. 1945 2N 6v positive ground. New wire harness. New Key switch. New Coil. New cut out, rebuilt generator, new points, cap , rotor, condenser. New 6v battery and cables. New resistor board. Put an indicator light in-line on key switch wire. All new wiring harness seems to check out correctly. Not 100% sure on resistor though.

Bench tested the dist. by grounding dist body with tractor battery +post, took an additional grounded wire to just off tang/tab on coil, ran - battery wire to top of coil, spark jumps between wire and tab on coil (the one which connects to contact on dist cap) when turning the distributor. Cap was off during this test.

Indicator light on key switch wire (in dash) blinks when cranking engine. 6v measured when reading between top of coil and -neg on battery with points closed (indicator light on). No voltage when light off. No voltage or light w/ key off. Tried for spark on tractor with 0.15 and 0.25 gaps. Both gave spark on bench test.

Dist back on and looking for spark by putting screwdriver in detached plug wire and holding over, just off top of plug. Also tried with new plug in wire grounded to engine. No spark.

6v measured from +bat to "common nut" where all wires meet on resistor board. 6v measured at both coil wire side of resistor and key switch side of resistor.

Tried old distributor cap and rotor w/ same results.

How I got here. Bought this tractor a few months ago and it was a makeshift neg ground 12v system. Ran ok. Had the original 6v generator so it was never charging the battery and I assumed it had to be charged every so often. Left key on once and it fried everything. I want to keep it original and converted the entire electrical system back to 6v.

Coil spring is touching nut good, tab on coil appears to be touching contact on dist cap fine. Rotor touching the top of dist cap fine. All contacts have been cleaned with emery cloth.

Any thoughts or suggestions would be greatly appreciated. Thanks.

Run a jumper wire from the non grounded battery terminal straight to the top of the coil. Does it start now? If so the problem is between battery
and the top of the coil. If there is still no spark then the problem is in the distributor.

From your description it sounds like you have the indicator lamp in series with the coil circuit. That will most definitely cause a no spark condition.

One side of indicator lamp should go to switched side of ignition and the other to ground. It will then light continuously when the switch is on.

(quoted from post at 19:41:24 12/07/21) From your description it sounds like you have the indicator lamp in series with the coil circuit. That will most definitely cause a no spark condition.

One side of indicator lamp should go to switched side of ignition and the other to ground. It will then light continuously when the switch is on.

Click to expand...

here he connected the lamp was a perfectly good test to determine if he has good continuity thru the key switch, resistor, coil, pig tail contact good, points making good electrical contact, and condenser not shorted. Remember, on 2N he has no distributor side of coil available to connect anything to. I would expect that he removed the lamp before trying to start the engine. If not, perhaps he will now.

I did not remove the indicator light before trying to start the tractor. I will try running a jump wire from neg terminal on bat to top of coil as suggested. I will also then remove the dash indicator light from the circuit. It must be the coil circuit because there is no voltage at the coil with the key off (points closed). It is on the yellow wire between the key and the "common nut" on the resistor board. I will report back tomorrow. Thank you all very much.

I tried the jump wire and it gave me spark. I took the indicator light out of the circuit and tried it without the jump and got spark. So that indeed was the culprit. It did not start, but that's a whole new upcoming thread . A lot of gas dripping out carb. Thank you all for your advice it is greatly appreciated.