It's a very wise move to just start from scratch with the wiring.(tip # 42)
You always need the OEM ballast resistor. You may or may not need another resistor depending on the resistance of your coil.
Technology & materials being what they were in the 30's, that square coil would melt if it ran on much more than 4 amps for any length of time. (see tip # 38 for an example). In order to get a hot spark at the same time the starter was drawing max current from the battery, a ballast resistor was added in the ignition circuit. What that did was add about .3 ohms of resistance in the circuit, added to the 1.5 ohms of the coil. That got you 3.5 amps or so at start up. As the voltage increased when the engine was running to about 7.5 volts, the resistor heated up, adding more resistance in the circuit. 1.0 ohms hot, plus 1.5 ohms of the coil got you down to 3 amps or so to keep from melting the coil. The same rule (actually, Ohm's Law) applies to a 12v circuit. I= E/R. Current equals voltage divided by resistance. So, measure the coil resistance & see what you have & then do the math.
I never buy tractor parts of any sort at TSC other than the sediment bowl gaskets. This site sells wiring harnesses as does nnalert's.
The front distributor was designed to come off of the tractor to replace/adjust the points. Remove the wire on the coil, remove the coil bail, remove the distributor cap & take the two bolts off. The base of the distributor has an offset tang & can only go back one way unless you really force it on. Look at how the points & condenser set in the distributor before you start pulling it down! Turn the tang on the base of the distributor & watch how the points open & close. The points open on the high point of the cam. The opening should be .015. Make sure the blade is at a perfect right angle to the points & you want to feel just the slightest bit of drag when you pull the blade through the points. Make sure the blade is clean & that you dress the new points by running some card stock or a piece of brown paper bag through them. If this is your first time doing it, draw a sketch! Make sure you are using quality parts; the points should have a phenolic rubbing block & not the cheap white plastic crap. Be careful not to ground the tip of the condenser wire to the body of the distributor when you replace the points. Do not break the little copper strip that goes to the points. (If you do, make another out of the old set of points) Also, make sure the condenser wire does not go through the same opening in the distributor that the coil pig tail does. The condenser wire goes the opening on the top right. Look at the old points; are they burned, pitted or mis-aligned? Make sure you have the star washers under the screws on the points.
Don't forget to set the timing before you put it back on.
Next, with the distributor still off the tractor, install the coil. Look at the pigtail on the coil; is it touching the brass screw inside of the distributor? Don’t trust your eyes; test for continuity from the top of the coil to the points. If you do not have continuity, stretch the pigtail a bit until you do. (some people would rather put a small washer under the brass screw) Look at the little tab opposite of the pigtail; bend it a bit also to insure that it will contact the distributor cap. At this point, I just put the distributor, coil & cap all back on the tractor as a unit (it helps to do this from the left side). The reason I do this is because it is real easy to get the cap or coil mis-aligned trying to put it back together one piece at a time & the result is something gets broken or you get a ‘no spark’ problem.
Lastly, check out tip # 39. a set of manuals will save you a lot of time & money!
50 Tips
