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Installing a Dewitt radiator and SPAL dual fans in a 1972 LS5 with air. What is the best source of power for the relays with Ignition on under the hood? Connecting the power wiring to the positive post of the starter. Many locations I would guess but want to avoid voltage drop if possible. Thoughts????
Installing a Dewitt radiator and SPAL dual fans in a 1972 LS5 with air. What is the best source of power for the relays with Ignition on under the hood? Connecting the power wiring to the positive post of the starter. Many locations I would guess but want to avoid voltage drop if possible. Thoughts????
I'm not aware of an 'Ignition ON' source under the hood. For my fan set up, I had to go to the fuse box to power the relay's themselves. I mounted my relay's right on the firewall and there are at least a couple of holes, close by, that you could use to route the wires from the relays to the fuse box.
Thanks for the quick reply. Fuse box is probably the best bet.
And if it's crowded (because they didn't give you a whole bunch of extra outlets, that's for sure), you can double up on a single, with a "two into one" female adapter and marry it up, with a low wattage demand source, like the yellow wire, commonly used to kick on the stereo.
Go to your wiper motor connector. The yellow wire there is an ignition switch controlled 12v source.
As a bonus it also will not provide 12v while cranking the engine so your starter will not be competing with the fans should the fans want to run during a start.
Fuse box is a good source, but I found the +12v at the horn relay to be good. You don't have to run as long a piece of wire..... +12v to a fan relay to the fan. I also installed a toggle switch to turn off the fan if needed.
Main fan power should run off the alt stud directly, with a 30+ amp fuse to the control relay, I mounted mine on the fan shroud just in front of the alt.....and left that heavy drag off the more or less stock wiring harness....the hot side of the control relay COIL goes to the yellow wire of the WSW motor....the ground side of the relay coil goes to whatever control the fans, sensor in the engine, or in my case the engine control computer.....since I have FI.....
anyone says to run the fan main power off the starter stud dunno WTF they are doing....CASE CLOSED@!@!!!
In 74 the power terminal on the alternator ran to a junction block mounted to the drivers side fender. This is a very handy place to get power for accessories that are controlled by relays.
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best 12 volt power source unde hood
