Alternator it is...
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Junior User
Joined: May 2016
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From: Freezing Minnesota
Alternator it is...
I decided to swap the generator for an alternator on my 49 F6 coe. The generator took a dump so rather than mess with that anymore, I bought the conversion bracket from Speedway,$39 and the 5/8 pully from speedway,$15. I then purchased a new mid 70's GM alternator from Oreilys for $45. I opted for a 2 wire alternator.
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Junior User
Joined: May 2016
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From: Freezing Minnesota
The fan/generator bracket setup that Ford designed defies logic, but we were able to get it installed. You have to buy new coarse thread bolts for the speedway bracket. The factory ford bolts are fine thread.
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Junior User
Joined: May 2016
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From: Freezing Minnesota
I wired it according to this diagram but used a diode in place of the lamp. I have the factory volt gauge to tell me if it is working. The diode prevents back feed of voltage.
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From: W. Central FL.
Some of these GM alternator installations will feedback into the ignition and prevent engine shutdown. That is why the diode or some kind of load is placed in the P1 circuit. It is rumored that GM and others put a resistive wire in the circuit to prevent feed back. The install in my 1949 F4 with EZ wiring kit worked fine for two years and several thousand miles and then the engine suddenly would not turn off with the key. Obviously getting feedback into the HEI system. I pulled the P1 wire from the alternator, taped it back into the harness, and all is working fine. I run a voltmeter so I can tell the alternator is doing the job. I suspect the P1 is used for exciting the alternator only and mine must retain enough residual magnetism. I am pretty familiar with electrical systems but just never figured it important to figure out the "why". I've installed several GM alternators on old Ford tractors and always installed a small marker light for a load. HPFM?
Cargo Master
Joined: Oct 2013
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From: in a barn
P1 wire needs some resistance to excite the alternator, I use a 120 ohm resistor or a idiot light depending on application, never heard of feedback into the ignition system myself. Maybe the internal regulator shorted feeding power back into the ignition switch?
Only resistor wire I know of in GM applications is in the ignition circuit of 1974 and older cars that used points, drops the 12v to 9v, but HEI uses a full 12v.
Only resistor wire I know of in GM applications is in the ignition circuit of 1974 and older cars that used points, drops the 12v to 9v, but HEI uses a full 12v.
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