Possibly a stupid question, but better safe than sorry:
When installing the FP voltage regulator (first time), do the mounting screws that hold the VR on the generator housing need to have insulating washers also? In other words, do the VR feet need to be insulated from the generator housing? Or do they get mounted directly onto the housing?
Don't want to mess it up and have to send it in for repair...
No. Furthermore, you should read through the install instructions 3 or 4 times before even going near the car. Make sure you understand it completely ... step by step.
Garnet - Thanks. I did read through them several times, and will again a few more times just to be sure. I didn't see anything about insulating the feet from the housing, so I thought I didn't need to, but wanted to confirm it to be sure.
Follow the instructions TO THE LETTER and you will have no problems. KGB
The feet need a good electrical connection to the generator body. If the feet are insulated it will not regulate, and will function only as a cutout.
You can all go to the head of the class. Every answer was correct and John H also has it correct that the ground of the mounting is a third electrical connection. I think it is basically impossible not to get an adequate grounding of the VR without using some sort of external insulting techniques. Incidentally original cutouts needed to be grounded too in order to operate the relay coil of the cutout.
If I recall correctly the original cutout mounted on the generator had a very thin shunt wire that ran from the generator side to ground. When the point were open and the car was running the current would have a path to keep the generator from burning up. Wonder if the cutout mounted on the wood firewall/dash had one? If it did how was it grounded?
Actually that is not exactly how it worked. The "thin shunt wire" was the cutout winding and it measured about 50 ohms and the diode cutout has no such wire yet the generator does not burn up. The idea is that when the generator spins fast enough to output a voltage that creates enough magnetism in the cutout coil then the cutout operates and closes the contacts which connect the generator to the battery. The diode cutout operates almost the same way except that the generator only has to put out enough voltage to forward bias the diode (typically .7V more than the terminal voltage of the battery). If using a mechanical cutout then you have to have the case grounded and the cutout that mounted on the firewall actually mounted near the edge with one foot hooked to the dash-to-frame bracket if I remember correctly. If that cutout were converted to a diode cutout then it could be mounted most anyplace on the dash except that the original location not only gave electrical ground but probably some heat sinking help too.
I know John Regan know this, but for those who do not, the 50 ohm (small) winding in the cutout is referred to as the "voltage winding" and the low resistance high current (big) winding is referred to as the "current winding". The mechanical relay in the cutout initially responds to generator voltage. The relay is normally adjusted such that when the voltage exceeds 7.2 volts the contacts close connecting the generator current source to the battery to the generator. When engine speed slows the battery current is higher than the generator and current in the current winding reverses forcing the relay contacts open disconnecting the battery from the generator. During this process there is much arching at the relay contacts. When engine speed increases the process starts over. The high current at the cutout contacts constantly going through this process is what ultimately causes cutout failure. This failure rate is high and reproduction mechanical cutouts made today are of very poor quality. For this reason you should consider converting to a FunProjects voltage regulator or properly engineered diode cutout.
Ron the Coilman
You are lucky! Model T's don't use a voltage regulator!