In Reply to: Re: Another look at the resistor posted by Farmer Dan on January 25, 2019 at 13:53:14:
I think you meant to say the drawing I posted is for the 9N/2N Dan. It is FIG. FO70 from the I&T FO-4 manual, see lower RH corner. A voltage regulator, p/n 9N-10505-A, was used on the very first early 9N-10000-A small 2-wire/2-Brush B-Circuit generator. The round can cutout and the 9N-10000-B generator were released to replace the previous electrical components. The 9N-B generator was now a 1-Wire/3-Brush A Circuit Design unit. This setup was used up thru all 9N and 2N production only the generator was revamped with a larger barrel for the larger armature to produce 11.5 amps output on the 9N-10000-C unit which was virtually the same internally as the 2N-10000 unit. The 8N model used a new 3-Wire/3-Brush A Circuit Design generator, output at 11.5 AMPS and a new voltage regulator. At s/n 263844 when the side mount distributor was released, the generator became a 20-AMP, 3-Wire/2-Brush, A Circuit Design unit and moved to the LH side of engine.
No 'N' ever used any fuse in the electrical circuit. Only the light switch had a 15A fuse and lighting kits were always dealer optional equipment accessories.
Now, here's my take on the Ballast Resistor. There are two styles, the 9N/2N unit and the 8N unit indeed, but the difference is in the mounting screws only, and nothing to do with its design and function. It is mechanically designed internally on both units. The 9N-12250-B resistor uses two 5/16-18 x 7/16 Flat Head Machine Screws, shown as p/n 24628-S7, to mount to dash. The 8N-12250-B resistor uses two #12 x 5/8 Flat Head Self Tapping Screws, p/n 41843-S8. I'm not 100% certain but the hole spread may be a bit different as well. I have a half dozen used resistors around somewhere so will look to see if I have one of each to compare. The way each one is wired into their circuits is different because the 9N/2N used the 2-wire cutout, the 8N used the 3-Wire VR; the 9N/2N used a 1-wire, no solenoid starter motor, the 8N used a 1-wire starter cable plus the solenoid had 3 wire connections. Nothing changed with the front mount distributor and coil assembly. The same wires are used for coil to resistor, ignition switch to resistor, with each model wired from their circuits. This is how I interpret the two resistors and don't see why each would have its own or require a different internal design. You could take a 9N resistor and use it your 8N and vice versa as long as you wired each as shown in their diagrams and could find a way to mount them. Just because each is wired a bit differently does not make them different parts, in my opinion. I could be wrong here, my wife says I often am, so if Bruce, JMOR, Soundguy or anyone else read this, please chime in.