1936-1948 Cadillac Flathead V8 12 Volt 80 amp negative ground alternator Installation Instructions
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This alternator is designed for the Cadillac Flathead V8 engine and mounts in the same location as the generator. Comes with 5/8” - 3/4” pulley this same pulley will work on both size belts.
Once installed tension the belt so it is just tight enough to prevent slippage, no need to over tighten.
There are two connections required for this alternator to charge properly. First connect the output of the alternator to the positive side of the battery or anywhere there is a direct connection to the + side of the battery. Do not connect to a switch source as the alternator needs to have constant voltage to properly charge. Use the correct size wire, we recommend 10 AWG copper wire with a 125 amp inline fuse.
Make sure that the alternator is well grounded all the way back to the negative side of the battery. If not, the alternator will not charge and can cause damage to the internal regulator.
Next connect the exciter plug Part number DSC130 into the socket on the back of the alternator. Then take the white wire and connect to a 12 volt switched power source. This connection can be directly to the ignition switch or to the + side of the coil (which is the same place electrically as the ignition switch.
If your vehicle has a generator light on the dash and you want to use this light to show when the alternator is charging. Instead of connecting the white wire to the coil or key switch, instead connect the white wire to one side of the generator lite under the dash the other side of the light will be connected tor the ignition switch. When the alternator starts to charge the light bulb will go off because the voltage across the light bulb will be equal thus turning off the generator light.
Once the alternator is properly connected, re-connect your battery leads ensuring that the negative side of battery goes to the frame and engine block.
Before starting, make sure the battery is fully charged with an external battery charger, then start the engine, increase the RPM from idle to about 800-1000 RPM, measure the output voltage is 14.1 volts +/-, this is the correct voltage to keep the battery charged.
If you are not getting 14.1 volts, stop your engine and make sure that all connections are tight and the battery is grounded to the ending and frame, grounds in these older cars are a source of electrical problems.