Maybe somebody can help me, I am getting desperate. I just got my 1948 8N after five years of off and on working on overhauling/restoring it had a three brush generator that I converted to a two brush per Service Bulletin 78. I installed an 8N10505B voltage regulator according to the great information I have found on this forum. I wasn't sure, but I used the wiring diagram on page 48 of the FO-4 for the 8N prior to serial number 263844. This 8N is has a front mount distributor by the way. When I got the tractor running it didn't seem to be running real smooth. I made some adjustments to the carburetor, but they didn't seem to have much effect. I even bought a new carburetor and there wasn't any difference. Also, when you increase the throttle, it starts to break down. The more you increase it, the more it breaks down. I made sure the carburetor floats were adjusted right, nothing seemed to change. I looked at the plugs and it looks like it is running very rich. I also bought another distributor. It didn't make any difference and I did check the points gap. I am thinking it is an electrical problem I have an extra coil which I swapped and no difference. It's almost like the spark is week and when you rev it up it is too week and runs worst the higher you increase the RPM's. One question I have is, when you convert the generator from to two brushes, as far as I can tell, aside from there being a different coil and distributor, you have the same components as in the diagram on page 49 of the FO-4 Should I be wiring it to this diagram and not the one for the early serial numbers? If I didn't mention it above, I did check the spark of each plug and they were all arching. By using the new regulator 8N10505B and the early serial number circuitry, is that, along with the ignition resistor, weaking the spark? I don't understand enough about electronics to know what the possibilities are. But I still would like to know why in the later circuit the battery voltage goes directly to the coil while in the earlier circuit it goes through a resistor. Does the later coil have a built in resistor? One other thing I need to mention is that, over a several day period, after having put my old distributor back in, it seemed to run fine for several starts and one time down the road, but then went right back to the way it was. Crazy! Could this be attributable to an intermittent short somewhere, but I still wonder about what circuitry I should be using. Thanks for any suggestions anyone can give. I don't know what else to try.

I would investigate why the plugs look carbon fouled. Adjusting the carb should make a difference in the way the engine runs. If it didn't, that should be checked. Test for a wek spark either with a spark tester or an old plug. If the iginition system is in good shape, a spark should be able to jump a 1/4 inch gap. If it doesn't, you need to find out why. I think you are assuming the worst and least likely of the problems you noted.

"One question I have is, when you convert the generator from to two brushes, as far as I can tell, aside from there being a different coil and distributor, you have the same components as in the diagram on page 49 of the FO-4 Should I be wiring it to this diagram and not the one for the early serial numbers?"

No. Front mount and side mount ignition systems are different, front mount should be wired as it is supposed to be wired, side mount should be wired as side mount is supposed to be.

"By using the new regulator 8N10505B and the early serial number circuitry, is that, along with the ignition resistor, weaking the spark?"

No. The only thing the ignition and charging systems have in common is they are both connected to the battery through the ammeter.

"But I still would like to know why in the later circuit the battery voltage goes directly to the coil while in the earlier circuit it goes through a resistor. Does the later coil have a built in resistor?"

The round can coil has sufficient resistance in the primary winding. No "internal resistor". The resistor used with the "square" coil is variable with temperature. Very low when cold, gets higher as the temperature increases. Its function is to provide a higher current to the coil when starting so as to compensate for the lower battery voltage when cranking, then to limit the current to the coil to a safe lever when the engine is running.

Please define "breaking down" in the context you are using it.

I suspect misfires and loses power possibly unless the throttle is advanced very slowly and then the issue still exists, however to a lesser degree. Correct?

Apparently William has a case of crickets.

It does seem that way

Ok, I am going to guess here a bit. as load increases, the engine sputters more... if I was to KISS this thing, I would be looking at firing order. it is TOO easy to cross 3-4 or 1-2 in the order. start there. then look and check for weak or off brand plugs. I am an NGK guy. have then in everything. Learned my lesson on my 8N front mount. won't run on anything but champions. go figure. then, it is flat a weak spark? next KISS would be to verify 6v + in the battery off, and at idle. next thing in line in my estimation is the capacitor. have seen far to many of these recently be bad out of the box. Next Kiss I think is to verify point gap. if Dwell time is not open long enough, weak spark becomes the issue. check the point gap, and if you are on the small side, try going to the large side.

Next question, have you verified compression? just off my nut thinking here, but low compression would show thew same as weak spark.... Baahhh... my two pennies, about all its worth. hope I helped, maybe I triggered a memory or idea... good luck !