Flickering Headlights

When the car is at idle the headlights flicker.

All things considered, would a higher output

alternator solve the problem?

Don't know the current capacity, I am guessing

in the 60 amp range. Would installing a 100 amp

alternator fix the problem. This is 41 year old wiring

so would a higher capacity alternator be safe?

Or is flickering headlights "normal" at idle (750 rpm)?

mike

Mike, a slight dimming is normal. I think the original was a 55amp alt unless you have A/C and or rear window defrost, then it came with a 65amp.

Mike, a slight dimming is normal. I think the original was a 55amp alt unless you have A/C and or rear window defrost, then it came with a 65amp.

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Correction. I checked my answer and the correct answer is:

The original alt was a 55amp if it was a 351-4v and/or if it had A/C. It would have a 61amp if has electric rear defrost and it was a Mach 1 or any model with A/C; or 55amp on all other models.

And, you only need a higher amp alternator if you were going to place more electrical demand on it. Standard loads, added a higher capacity alternator would give no change in operation. I would guess that your current alternator is getting weak, or I think there was an earlier post that made reference to altering the lighting circuit to give more stable power to the headlights. Its hard to check varying voltage with a digital meter, because they don't react fact enough, if you could find an old analog voltmeter, I bet you would see the needle bouncing with your dimming lights.

Don't have an analog meter but my digital Fluke might work. It reacts pretty fast.

Forgot to mention but sometimes when I set the heater's blower on high it would kill

the engine. That could be a problem. My concern is could a 100 amp alternator be

harmful to the 41 year old wiring. Or does the alternator only produce amps as needed.

Another concern being ordering a new altenator. Most vendors offer a 'one wire'

alternator. There is more than one wire attached to my alternator. My Ford wiring

diagram shows two wires for a car with a tach and four wires for a car with gauges, my

car has both.

mike

I would replace the regulator with a electronic regulator. If you are worried about apperance, you can take the cover off the existing regulator and put it on the new one.

I once had a problem with headlights flashing on and off -- it was the headlight switch. My switch got really hot when it was failing. It is easy to reach your hand behind instrument panel and feel it (behind pull out knob used to turn on headlights).

If turning on the heater blower is killing the engine would look for a short in red wires with blue or green stripe. I believe current across red wire with blue stripe is during engine startup and after engine is started -- red wire with green stripe.

I would replace the regulator with a electronic regulator. If you are worried about apperance, you can take the cover off the existing regulator and put it on the new one.

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We will probably replace the main buss from the regulator to the

firewall. My mechanic tells me it feels a little stiff indicating age

and that will affect capacity.

Just need to find what size wire is used. This is a single wire, #37A

in the diagram. The regulator is new from MartiAuto.

mike

Clean all of your grounds. You may be suprised.

Clean all of your grounds. You may be suprised.

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All ~57 grounds :huh:

Really, that is a good suggestion :idea:

All the other lights work fine, just the headlights

flicker but they use the most amps.

mike

With all the work you;ve done. Those grounds are a great place to start. Throw some contact grease on them if you any.

Hey Mike,

my car did the same flickering routine, but my dome lamp and gauges joined in the game as well.

I ended up rewiring the headlight circuit pulling the power directly from the battery through relays and all the flickering is gone.

here is a link on how to:

http://www.midnightdsigns.com/james/headlights.htm

I think its just too much of a load running through the headlight switch.

I vote do the relay & see if it helps, cant hurt plus it's fairly cheap to do.

I've heard good things about using relays.