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Alternator question

4

440fish

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So i have what id call a "marginal" electrical system on my 69 SB for some time. Has the typical flickering of lights etc when everything is turned on (headlights, turn signals, brake lights.) When i sit at a traffic light at idle this is really exasperated. Was able to live with it but once i upgraded to a MSD ignition i've found that the MSD really gets upset when the voltage drops... even to the point where it starts skipping. Over time it it seems to get worse and i yanked a few plugs to find they are getting fouled due to what i believe is lack of power to the msd at idle. (no it isnt a jetting or timing issue, Tuned car with a A/F meter)

Bench Tested my 1 wire round back alternator and it is a 40 amp model. Found a 70 amp 2 wire square back and had it completely rebuilt.
My questions are this after doing research:
1. Should this upgrade solve my weak power at idle?
2. will the stock harness handle the upgrade? I thought it would be fine but the auto electric guy said you need to be sure that there wasn't an upgraded harness for higher amp applications (hes not a Mopar guy)
3. Should i bypass the amp meter at this point.

thanks!
 
It will help but adding relays to the circuit will be more beneficial. I would also upgrade the wire for the alternator if you make the switch. And yes to bypassing the amp meter.
A lot of your questions and how to can be answered by going to
http://www.madelectrical.com
 
For what it's worth, I had the same dimming feature when I'd hit the brakes or turn signals. I needed to replace the alternator (whole other story) and what I found was a badly corroded connector to the alternator. Once cleaned, the new alternator handles the load just fine at idle. No more dimming headlights and the volt meter does not jump around anymore either. Just something to think about.
 
1. Probably "yes", but I'd also check the ground wires all over the car which are usually rusty/bad. Also, I've "heard" you can get different alternator pulleys and "over-drive" the alternator (smaller pulley turns faster at idle).
2. I think the stock harness should be fine since the wires don't appear to be different sizes between my old '69 Roadrunner & my '70 Roadrunner, but adding an extra wire from the big/hot terminal directly to the battery could only help.
3. Yes
 
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I think what 69a100 was referring to was a 70's style regulator. If you are using a 2 wire alternator you will have to use the 70's voltage regulator unless you ground one of the fields then you can use your old regulator. The first one is for a single field alternator(69 and earlier. The second is for a 2 wire alternator(70 and later)
 
That's what I ended up with. I flip flopped back and forth with the 1 wire and 2 wire and eventually decided on using these with a 2 wire alternator and 1 of the fields grounded. Looks original and working fine.
I ended up getting mine from
http://www.4secondsflat.com/regulator_tech.html
 
1) What was different about the one you got from Napa?
2) I thought you used the mechanical one?
3) People still listen to AM?
 
Thanks for the info guys. Going to upgrade to the 2 wire and newer style VR.

thanks!
 
I had the same problem. My turn signals would not blink if sitting at a stop. The battery was not charging properly. Newer electrical components were bought trying to find the faulty area.
Replacing or upgrading the wiring was the fix. New wires and new links too. No need to replace lots of electrical components. Just redo your wiring.
I was rattling my brain trying to find the problem. Thought it was the alternator, or the voltage regulator, or something else.
I bypassed my ammeter because of other reasons.

Good luck! Everybody knows electrical problems are a headache.
 
I have the mechanical on my 66.
The 71 and 72 Darts had the electronic style, and that's where I found the cheap one made radio noise.
I ran a radio station on AM 1620, so naturally I wanted to listen to my own music.
I keep telling everyone it's the way the stator is wound that makes for weak output at low rpm.
Find an alternator with 12 turns per loop in the visible windings, and you will have plenty of juice for turn signals to work correctly.
 
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