Installing an electric fan on my 73 can I do it myself without messing up?

[WH23G3G]

Despite what my general mechanic tells me I know my 73 400 Charger does need or will eventually need an electric fan installed. So I'm debating whether to install myself. Can it be installed in front of or behind the radiator? I have a 28" radiator, original shroud, new clutch fan, and the big original 7 blade fan, I think it's like 20+ inches, it's the heavy duty a/c fan blade. Back in the summer here in Georgia when I did drive it that one time in the summer the gauge stayed in the middle but at slower speeds or idling in the 5:30 traffic it tried to creep up to H but it never got too far. I told my general mechanic it needs an electric fan but he said but it doesn't overheat. It was overheating when I originally brought it into him last summer. He said it was just the thermostat. He said he let it idle for hours outside and it never got past the middle on the gauge. To lessen the possibility of getting overheated again I just want to install an electric fan I can switch on if the gauge gets too hot. Where's the best place to install it? What's involved with wiring it correctly and professionally looking? I've got new engine harnesses from Year One that I don't want to hack into if it's avoidable. What's the best way to do this?

[A383Wing]

you will need a pusher fan to mount in front of radiator, or a puller fan mounted behind the radiator. Use a relay and a toggle switch inside the car to turn fan on and off at your command. Take power for the relay from battery and then go to fan motor

is your fan clutch thermal style or non-thermal style without the spring in it? If it's the thermal style, it won't engage the fan until a certain temp from the radiator, by then, it may be too hot. I run a non-thermal clutch on mine so the fan is spinning faster at lower rpm and disengaged at higher RPM while cruising down the road

[WH23G3G]

Yeah mine is the thermal type because again my mechanic said if I install a torque drive fan I'll have even more overheating problems. But all the research I did for back in 73 it appeared the 440 and 400 with a/c came with the torque drive fan. I can always try it out. It doesn't take much to swap out the fan clutch. My mechanic said I worry too much, but I asked him could it have been because this is a 76 block thin wall casting and it's bored .040 over? He said he's seen Mopars with 400s like mine pushing way more HP and Torque bored with no cooling problems. Mine is built stock specs but for the .040 over. Stock heads, HP manifolds, I know that doesn't help the heat either. I still want to install an electric fan just for insurance. What's the smallest I could get away with?

[oldcarnut]

Another alternative to mounting a switch for turning on and off is to use a auto thermo switch to turn it on/off at the temp you want.  Then you or whoever is driving doesn't have to depend on actually seeing the gauge to catch it in time. It will shut off on its own when the temp drops.
http://shop.advanceautoparts.com/p/flex-a-lite-electric-fan-temperature-switch-31147/10318621-P?searchTerm=electric+fan+switch

[A383Wing]

Sounds like your mechanic doesn't know much about clutch fans and how they work. But that's between you and him.
I would get at least a 16" pusher with around 2,000cfm rating

[b5blue]

You need to be certain your alt. output is enough to feed the fan at idle? With no upgrade in that area it's a weak point. I run a solid mounted after market stainless steel fan with no shroud down here in FL. with no problems. At lower speeds the blades pull a bunch of air as they are curved more than factory.

[WH23G3G]

I got the 60amp alternator. I also have all new factory a/c installed but I haven't vacuumed and charged it yet. Is it ok to install the electric fan on the condenser or will it even do anything?

[A383Wing]

you can mount it on the condenser

[b5blue]

Check idle output on the 60A alt. by turning everything on and looking for a voltage drop with a meter. If voltage is significantly lower amps will follow.  (You would need to address that before proceeding.)

[Brass]

Check idle output on the 60A alt. by turning everything on and looking for a voltage drop with a meter. If voltage is significantly lower amps will follow.  (You would need to address that before proceeding.)

How much of a drop would be too much?  For example, if you go from 14.5 down to 12.5 wouldn't that still be okay?

[b5blue]

   The mindset I'm trying convey is how far can you weaken ignition spark before "at idle" the car is drawing off the higher potential of the battery to keep running. You can get a see-saw effect draining the battery then when you increase RPM's output jumps but now meets demand AND must recharge the battery. (I don't have amounts for you there are too many variables.)   

[red79]

Check idle output on the 60A alt. by turning everything on and looking for a voltage drop with a meter. If voltage is significantly lower amps will follow.  (You would need to address that before proceeding.)

How much of a drop would be too much?  For example, if you go from 14.5 down to 12.5 wouldn't that still be okay?

Generally you want your voltage to be a rock steady 14.5v no matter which accessories are operating. When you max out the capacity of the alternator, then you start drawing from the battery, and you'll see the system voltage drop to ~12v. Not a condition you want to maintain while creeping along in freeway traffic; a big aux fan and headlights can drain a battery awfully quick and leave you SOL.

[b5blue]

  A good "real world" check is to just turn everything on and off with varying combinations. At idle, do the lights dim or wipers slow? Blower speed reducing? Motors starved for volts work harder, not good. If lights are dimming, motors are slowing, you can bet the ignition is suffering also. If everything is fine proceed.

[1974dodgecharger]

yup, I was killing batteries monthly not realizing I needed an upgrade and happens to a lot of people and don't understand why they are killing their batteires every so often and assume its a leak somewhere, but sometimes its just they don't have enough alt. juice.

Check idle output on the 60A alt. by turning everything on and looking for a voltage drop with a meter. If voltage is significantly lower amps will follow.  (You would need to address that before proceeding.)

How much of a drop would be too much?  For example, if you go from 14.5 down to 12.5 wouldn't that still be okay?

Generally you want your voltage to be a rock steady 14.5v no matter which accessories are operating. When you max out the capacity of the alternator, then you start drawing from the battery, and you'll see the system voltage drop to ~12v. Not a condition you want to maintain while creeping along in freeway traffic; a big aux fan and headlights can drain a battery awfully quick and leave you SOL.