Have a 73 Comet with 302, installing a electric cooling fan and need a good 12 volt key on source for relay, where is the best place to pick this up in the engine bay( dont' want to use 12 v ignition source wire for distributor)
Use any keyed 12v source to trigger a relay so the actual power source for the fan comes directly from the battery.
Is there any wire on the voltage regulator I can use that is 12 volt source when the key is on the ON position
I think Frank "71Gold" was asking what are you using to activate what temp the fan activates. Are u turning in on/off manually w/ toggle switch or using temp sensor to activate fan?
I'd get it from the choke circuit. It has 12 volts only when the alternator is spinning. Send that to the relay...
Where is the choke circuit wire at? I have a manual choke on my holley 4 barrel carb, what color is wire
Choke voltage from alternator stator is NOT 12v. With engine running, it's approx ½ battery voltage. Choke heaters on factory inst carbs were 7v units. Connecting those to 12v soon burns out heater. Connecting modern 12v choke to stator, results in lazy choke operation. Whether a relay will trip on 7v depends on it's coil resistance, some will, some will not. It is possible to use the ignition lead to power a relay, will drop voltage to coil approx .2v. Or a negligible amount.
Wow, I never knew that. My Maverick has the stock mechanical fan, but I have a GM project car that I am installing an electric fan on, and I'm pretty sure the Choke/Heater circuit is 12 volts on that car, but now I'm gonna make sure before I wire it that way. Thanks!...
Your right as to relay voltage requirements. I had my fan hooked to a source I discovered had fluctuating voltage; fan worked fine for a few years -- all of a sudden car started overheating. I changed relay to a known constant 12v , never had an issue since. I don't recall exactly where I had the relay power source and puzzled it worked ok as long as it did. I am still using the same relay, just different power source -- only thing I can guess -- relay resistance may have changed over time..
