Maybe Altenator issue?? Need help

[Automan]

Hi Everyone, My 63 1/2 427 cobra from Antique and Collectible is having some power issues. So im driving and my alt-meter gauge shows 14 amps and in the green. When i turn on the cooling fans it drops alittle to about 12 amps. But if i turn on the headlights, amps drop to yellow and the engine seems to loose power. If i stop at the lights, the engine struggles to idle and the needle is in the red.

I have a new Battery installed, and the only other thing that i did was install a auto cooling fan and shroud from Summit Racing.

Any advice??
Thankyou
Nelson

[LMH]

14 Amps? Or volts?
Larry

[DanEC]

I think he means volts. At idle with the electric fan(s) running and the headlights on, I would not be surprised to show the voltage across the system to drop to 12 or lower. The load on the alternator might also pull the engine idle down somewhat. Blip the throttle and it should pick up to 14 volts immediately. You can probably raise your idle speed a little to counter this. Do you know what size alternator you're running? Possibly one with a little more amperage output could improve this considerably.

Another possibility would be to wire an idle speed solenoid in on the carb to raise the idle when the fan kicks on - but typically these solenoids are not powerful enough to push the throttle open without a blip of the throttle first. So, it may not be worth the effort.

[MOTORHEAD]

re; low power, if you're running an ignition box and the voltage drops too low, it might cause the ign to cut out.

[saltshaker]

I had a similar problem, I use a Mark Vlll fan which draws a lot of amps and solved it by running a #8 wire from the back of the alt to the batt side of the selenoid. Do you have a thermostat switch connected to the fan or is the fan always on ? ...that makes a difference too.
Jon

[427sharpe]

That is very low, assuming the alternator itself is in decent condition and not on deaths door. What alternator are you running? I presume the used-forever-1G that Ford used all thru the sixties and seventies? If so, you may consider changing over to a new style Ford 3G, which is the common alternator now for the electronically laden, fuel injected cars and will supply power out the wazoo for our simple machines. They come in 93 or 130 amps, internally regulated and a very simple DIY install. Even fits the same brackets if you mind the case sizes. Plenty of articles/info out there on the net (surf 'Ford 3G upgrade'). Wiring is a snap and 93 amps replaces 60 or so in about 20 minutes.

[427sharpe]

The green 'I' wire is ignition, of course.

[Automan]

Yes, volts. Sorry

[Automan]

Im actually seeing the needle drop while i am running the car even on the highway. I have a 65 volt alternator that is seven years old.

[Automan]

I have a thermostat switch relay that i have it set to turn on at 200 degrees. I also have the dual pusher fans that i use manually. because its manual, i was able to turn them on when i turned the lights on on the highway and seen the needle drop to low yellow and almost red.

[Automan]

65 amps alternator. early to mid sixties type

[jhv48]

There's the problem. Most cars have at least a 90-100 amp alternator. Yours can't keep up when all the accessories are on.
Fans alone can eat up 50 amps. Add the headlights and you're maxed out. Time to upgrade.

[Automan]

So i currently have a Remy 20155. Thats the part number. I have 3 leads going to it. I should probably get this one rebuilt to put out more amps.

[Automan]

My setup is very basic. 427cid with points distrubutor with a electronic module inside. Dual 650 holley carbs. No fuel injection. Mechanical fuel pump and no heater or radio.

[Automan]

This is the Fan shroud that i installed.

Branderale Cooling Products
Manufacturer's Part Number:16822
Part Type:Fans, Electric
Product Lineerale Performance High Output Single RAD Fan and Shroud Kits
Summit Racing Part NumberER-16822

UPC:083277168222
Maximum Fan CFM:2,400 cfm
Fan Quantity:Single
Fan Diameter (in):17.000 in.
Height (in):17.625 in.
Width (in):22.250 in.
Thickness (in):3.000 in.
Number of Blades:11 blades
Blade Material:Plastic
Blade Color:Black
Shroud Color:Natural
Shroud Material:Aluminum
Amp Draw:23.50 amps
Air Conditioning Relay Included:No
Mounting Brackets Included:Yes
Mounting Hardware Included:Yes
Quantity:Sold individually.
Notes:Two speed motor, 1,800 cfm at low speed drawing 17.4 amps.

[DanEC]

Well, the headlights probably pull up to 20 amps on high beam, less on low beam. That combined with the 23 amp fan and tail lights, parking lights, dash lights, etc would probably be marginal with a stock alternator at idle. It could also be that your alternator is a little on the weak side. It might be a good idea to pull the alternator and take it down to an auto parts store that can test it and see if it's putting out like it should. I would also check all your grounds to make sure they are good. And, I would check the temperature of your wiring to the fan when it's running. If it warms up considerably, possibly it's too small of gage for that fan load and pulling an excessive load on the alternator.

[RICK LAKE]

Automan Are you running March pulleys? Are they under driven? This is problem #1. Alt is not spinning fast enough to both recharge the battery and running the whole electrical system. 65 amp will run a basic cobra car without alot of extras. You need to take the ALT to a Autozone and have them check the MAX output of the ALT. If it's passing the test Want to see 60 amps min. This will work if you are at crusing speed, say over 1,500 rpms on the motor. Wouldn't run everything at 1 time.
Pulleys, if you are running any underdrive pulley setup on the crank shaft, this is another big problem. The Alt is spinning too slow and can't charge the system and the battery at the same time. You may be getting only 25-30 amps and need a 40-50 charge to keep everything with the correct voltage to system. You should have a 1-1 ratio on the crank pulley and waterpump pulley and about a 2-3" Alt pulley. Underdrives are for racing, 1/4 mile cars, or show cars. They work boardline when cruising( depending on rpm range).
Wiring last thing, Make sure you have a fusable link in the output cable of the Alt. I like a 150 amp fuse and #8 wire in copper.
I run 3 coolant fans, 3 blower fans for heat, 2 fuel pumps, ECU, fuel injection system, Lights, MSD igntion. I have gone to a PA preformance setup. They sell a kit that hooks up to your Orginial harness with voltage regulator box and heavyduty output cable. I went to a 95 amp setup and it powers everything. You CAN'T run a amp gauge with this setup. IT melts the insolators on both SW and Smith gauges over time. You get one hell of a fire too. You don't want to let out the smoke in this curcuit. Check into PA for their cobra kit. LIfe time warrantty on their system. Racing 5 years, no problems. Good luck. Rick L.

[Ron61]

I had much the same setup on my Cobra that Rick describes except I never had any under-drive or overdrive pulleys and I had a 100 Amp alternator built. When everything was on and I was racing the voltage would only drop to about 13 volts. It may drop to 12 for a second when I turned on more fans or something but it came right back up. Also you may want to check all of yur grounds.

Ron

[slithering]

Hi Automan, If you are still experiencing your voltage / amperage issues, here are a few suggestions. Definitely upgrade your alternator to a 90 amp. with dc voltage, when there is a drop in voltage there is a drop in amperage and this is damaging all components. Your cooling fans need an independent ground going to frame.
I have a 427 sideoiler with a 4500 cfm cooling fan and a 90 amp alternator. My cooling fan is wired as it's own system with a 60 amp fuse and a 190 temp switch. I have no issues.