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Stock 70Amp Alternator and electric fan
#1
Need to add an electric fan for cooling in heavy traffic. Will the stock alternator on my 73 vert w/AC be enough or will I have to upgrade?
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#2
Do you have any other power consuming upgrades like stereo/amplifiers, electric fuel pump, electronic ignition, EFI, etc?



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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#3
No doubt you'll need a bigger alternator. Is it going to be a dual fan? They draw 30 amps apiece. And with the AC (especially if stock) and the inside blower on you are going to be sucking a lot of power.

If you have any of the options listed by Don, it is a real vampire.

I had upgraded to a 150 amp before adding the radiator fans (dual Spals), and just installed installed a 320 AMP. My biggest issue right now, it that these alternators do not fire up until around 800/1000 RPM so at idle I am sucking off the battery. I am looking for a smaller alternator pulley, but what I have currently is pretty small, so I'm not sure that I can go down any. If not, I'll look into the feasibility of doing something with the pulley on the motor, but have no idea is anything can be done there, it looks like the pulley to drive the alternator is in the middle between the pulley for the power steering and the one for the water pump (fan removed from that one)

Do you have a volt meter in the dash ?

73 ragtop, 1999 Mustang Bright Atlantic Blue Paint, Phoenix Engine 302-335HP,  Edelbrock Carb & Performer manifold; c4 with 2000 stall and shiftkit; 3:55 auburn limited slip differential, Hedman shorties; Car Chemistry Exhaust

Classic Air; Tilt Steering Wheel; 1999 Chrysler Sebring bucket Seats ; power windows;
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#4
(07-22-2018, 02:53 PM)mudbilly Wrote: No doubt you'll need a bigger alternator. Is it going to be a dual fan? They draw 30 amps apiece. And with the AC (especially if stock) and the inside blower on you are going to be sucking a lot of power.

If you have any of the options listed by Don, it is a real vampire.

I had upgraded to a 150 amp before adding the radiator fans (dual Spals), and just installed installed a 320 AMP. My biggest issue right now, it that these alternators do not fire up until around 800/1000 RPM so at idle I am sucking off the battery. I am looking for a smaller alternator pulley, but what I have currently is pretty small, so I'm not sure that I can go down any. If not, I'll look into the feasibility of doing something with the pulley on the motor, but have no idea is anything can be done there, it looks like the pulley to drive the alternator is in the middle between the pulley for the power steering and the one for the water pump (fan removed from that one)

Do you have a volt meter in the dash ?

No voltmeter, just the original idiot light.  Replaced the original AC with complete system from Classic Auto Air.  No other add-on electrical accessories. Stock power windows.  Looking a Flex a lite single fans that are advertised to draw 15-18 amps.
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#5
(07-22-2018, 01:08 PM)Don C Wrote: Do you have any other power consuming upgrades like stereo/amplifiers, electric fuel pump, electronic ignition, EFI, etc?

No other electrical add-ons. Power windows and factory radio. Looking at single fans that advertise 15-18 amp draw
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#6
You might be OK, assuming you don't raise and lower the windows or top frequently.

If it were me I would covert to a 100 to 130 amp internal regulator alternator. They're not that expensive and would provide good peace of mind.

At a minimum I would get a voltmeter that plugs into the cigarette lighter in order to monitor the battery voltage.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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#7
I'm also assuming that you are adding the fan to the front. A properly operating mechanical fan, with a good clutch and a fan shroud that is the correct size for the fan will pull a lot more air than the single electric fan that just pulls 18 amps.

Other things to consider are a clean radiator (inside and out) and a.c. condenser. Timing that is off will contribute to overheating as will improperly adjusted carburetor. The thermostat also has to be the correct one (especially for a 351C) and operating properly.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
  Reply
#8
(07-22-2018, 05:17 PM)Don C Wrote: I'm also assuming that you are adding the fan to the front. A properly operating mechanical fan, with a good clutch and a fan shroud that is the correct size for the fan will pull a lot more air than the single electric fan that just pulls 18 amps.

Other things to consider are a clean radiator (inside and out) and a.c. condenser. Timing that is off will contribute to overheating as will improperly adjusted carburetor. The thermostat also has to be the correct one (especially for a 351C) and operating properly.

Thanks for the info. Looks like an alternator upgrade is on the list. I have installed a new factory style radiator and replaced the thermostat with a new 195 cleveland specific one. no clutch on fan, appears to be factory 5 - bladed. fan shroud appears to be factory and is a good fit for the fan and radiator.  The aftermarket condenser mounted in front of the radiator appears to be the culprit. Its pretty large and dense and I suspect restricts airflow in heavy stop and go traffic just enough for it to heat up. I can rev the engine and temp will slowly come down, but with flomasters on the car, not something I want to do all the time sitting in traffic. I don't know anything about electric fans or how large it needs to be.
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#9
Installing with relays is a must and have a manual switch+extra adjustable sensor/switch is handy too (so they keep turning or start after engine is shut down).
An healthy strong battery is a good idea, even more if you have an extra sensor like I do. As they can stay on after engine is turned off for while sometimes.
Tho, mine is set just above operating temp, as we do not have a very hot weather here and they rarely stay on for a long time.

73 modified Grandé 351C. Almost done. 
71 429CJ. In progress
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