I'm trying to figure out the butchered wiring in my 65 Bel Air. The engine is a 69 307 with HEI, and I think the alternator is internally regulated-when I took it to the parts house, they said it was from a 78 Camaro. The car also did not have a horn relay when I got it. I need help to wire everything correctly, like the alternator and external regulator (if I need it) and the horn relay. The alternator is a 3 wire, but the batt wire and the red wire coming off the 2 prong plug are spliced together, along with another wire that goes down to the starter. I have a copy of the stock wiring diagram to help, but with the changes done, I'm not sure where to start.
Two of the alt wires can be hooked together, the third one can run to the "R" terminal on the starter seleniod, thats what turns the alt on (excites) when you crank it over. as for the horn relay, thats switched thru the ground. Post a pic of what you got and I'll help you thru, if your using a bosch style relay,,, the 30 and 86 terminals get 12 volts, hot all the time if you want the horn to work when ignition is off, the 87 terminal goes to the horn itself, the 85 terminal is the ground so that one goes to your switch. HEI requires a full 12+ volts all the time so make sure that there is no ballast resistor or resistor wire running to it. If there is you can scab in another wire from the fuse panel, just make sure its hot with the ignition on and when cranking.
Pretty basic stuff. Don't get frustrated with it. One wire at a time and you'll be up and running in no time...........
Wire going from alternator to R terminal sounds wrong. Yes it will excite the alternator into charging, but what about when you release the starter. The R terminal ceases to have 12V on it when starter is not engaged. Yes, it may still charge due to the internal regulator, but I would rather have a good exciter voltage source to the alternator. A better approach is to connect the wire (that you think goes to R on starter) to the accessory post on ignition switch. That should solve the problem.
works everytime, no problems. once the alt is turned on it stays on until it stops spinning. there is no need to continue supplying 12 volts to the exciter. been doing it that way for a long time and its always worked fine. if your using that terminal to feed 12 volts to the points/ignition during cranking add a diode in line somewhere just in case. With an HEI there is no need.
So if this is the case then why did GM wire to the ignition switch (thru the idiot light) or not even wire it, just connect to battery terminal? Doesn't a one wire alt wire up all wires to the battery term on alt? Funny thing, my 59 Olds has a 10 or 12 SI on it. The field wire is connected to the idiot light wire, so that an indicator for no charging is present. Well when I start it up, the idiot light will stay on, even though the engine is running at good idle speed. Only way to get alt to start charging is to rev up! After that everything is fine. Go figure!!!! I am thinking since the sense wire is not present that there is no physical presence of 12 V at the internal regulator. Going to look at the voltage regulator schematic and ****yze it.
standard gm alt will self excite at 1200 rpm, so if its not exciting at idle your not getting 12 volts to the excite wire. Run a new wire to the "r" terminal and see if that cures it. If you put a constant 12 volts to the excite wire you'll end up with a dead battery and probably cook the alt.
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