I've had my 66 6 cyl for about 10 years. Ever since I've had it, it's been going through alternators routinely. The most recent one I put in about 4 weeks ago and it went bad the other night. When I changed the alt, I also changed the voltage regulator. When I went to go get the vr from a local parts store, the first one that the guy brought out was about twice as "tall" as the ones that have always been in the car. In looking at some of the mustang parts stores online, it looks like I am supposed to have this one in the car. It's got air conditioning which appears to make a difference. I remember him saying it was a "transister" vr, which doesn't mean anything to me. Could this be the reason that it's burning through the alts? Short of ordering one online, is there a way anyone knows how to shop for one in a parts store? Are they rated by the amount of voltage or anything? I would just order one online, but I need to get it running this weekend as it has become a daily driver since my other car needs an engine overhaul. The fuses blow all the time too, particularly the heater fan fuse. Any help will be much appreciated!

 

sounds like you got some serious electrical issues and the transistor vr are nice cause they are more consistent and i would be looking for shorts/grounding problems cause thats what it sounds like you have

 

I do have a grounding problem right now. The left headlight is dim and I think it's because the left turn signal bezel rusted through. I've taken out all of the aftermarket stuff that the previous owner put in. He had an alarm system and and a stereo in it. I'll try the transistor vr and see if that helps. I do need to just rewire the whole car, but not when it's the only thing I have to drive. Thanks for your help!

 

Your turn signal and the head light are different grounds. What amperage alt do you curently have? A non AC car would be around 45 to 55 amps( with some electronics). With AC, 65 amps. Now if you have an electric fan and/or extra curent draw then 90+. After exhausting some time by swapping voltage regs, you can buy a one wire alt with an internal reg. This will eliminate the external reg all together. "Don't buy reman alt because they do not last" I have read that alot of guys have problems with them.

 

I have an Alternator that is rated less than 55 amps, and I have an AC car. It works just fine. You don't need anymore than that unless you are running some pretty serious stereo equipment. The Voltage regulator can be picked up at any parts store. No need to order online. I don't think you can even get a mechanical VR anymore, so you will be getting an electronic one. Here's mine.


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no you can mechanical one i have seen them i just don't remember off the top of my head

 

The standard replacement at Checker for some of these old beasts is a mechanical VR. They tried to sell my one for my '65 when I had the blinking light problem. I told them to try again.

 

Oh, OK. I specified an electronic VR when I replaced mine with the new alternator.

 

Just running your lights and at a stop light at night you draw 30 Amps. Now add on a AC or blower motor, 5-9 amps each. Then try to charge a battery at the same time. A 45 amp alt will work but you will not get a very long life out of it. Alt runs hot and draws alot of HP from the motor when running it it at near 100%.

 

Man...I better upgrade that 20 amp fuse for my headlights!!!!!

FYI...55 watts (headlight) is only 4 amps. Times 2 is about 8...maybe 9. No other light in the system is that big. Add 3-4 for all the others, for a total well under 15 amps. The ignition takes maybe an amp (my MSD takes approx 1 amp per 1k rpm, so a stocker will be a bit less). Blower motor, AC relay, and radio (not thumpin' stereo) don't really draw a whole lot, either....less than the lights for sure.