Upgrading 37amp Alternator to a 50amp?

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mmdoctor

mmdoctor

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Guys,

Have a '67 Notch and my alternator went out. I know the stock rating was 37amps but would like to upgrade to a 50amp if there are not going to be any wiring issues (fire hazard, melting wires/harness, etc)?

I'm assuming just going up 13 amps over stock, I should be fine but just wanted to be sure.

Thanks in advance for any help!

- Chris
 
I don't see the 13 extra amps being a problem to the bulkhead connector but that's always a good upgrade regardless. Lets see if slantsixdan will chime in on this...
 
The thing is, your bulkhead connector could very well ALREADY be in what might be called a "weakened state." Something about 44 years of rust, corrosion, heating, etc

I suggest you read the Mad Electrical article on the subject. Regardless of what the god of the internet might think, there IS some good food for thought there

Marginal sized wire, too small connectors, and poor design of the ammeter itself

http://www.madelectrical.com/electricaltech/amp-gauges.shtml

from this page

http://www.madelectrical.com/electrical-tech.shtml

I grew up an "ammeter man." It took a long time for me to finally think about "throwing in the towel" and I'm STILL thinking about building a remote shunt ammeter so I can keep my beloved instrument.

Back "in the day" I had a 70 440sixpack RR with what was alleged to be a 60? 65A optional alternator. Both the original owner and I were radio amateurs, and I DID HAVE some amateur gear installed part of the time, as well as 4537 aircraft landing lights --2X 100W lamps

Even back then, I already had problems with the bulkhead, befor Al Gore invented the internet, and before I ever heard of the problem.

My solution then-- which I thought of all by myself-- was to drill out and run larger gauge wire through the bulkhead.

I've also run into a number of '70's Dodge pickups, typically with snow plow setups--or winches-- that literally melted the ammeter right out of the back of the plastic dash.
 
If you dont plan to use more amperage there's really no need to change anything. If you do plan to use more amperage You will need to provide a sufficient path. Whether that means simply clean, inspect and test what is there or
go ahead and upgrade the path to conduct as much as 80 amps without fail is your decision.
 
Thanks for the info. I don't plan to add any increased amperage now, but plan on putting in a new ignition (Crane Hi-6) in soon and adding an aftermarket stereo down the road - something very basic, not some giant sound system with external amps, big speakers, etc.

I already purchased the 50amp, but just wanted to ask the experts before I install and fire it up. I'll check the bulkhead connector for anything that looks out of the ordinary. If that looks okay, I'm assuming from mtandrews response that no upgrading of wiring is needed with this new Alt.
 
The point is NOT how much more you are adding (or not), it is whether what you have is damaged NOW. This can only be determined by a combination of visual inspection and voltage checks UNDER LOAD.
 
Is the 50A alternator isolated field (2 connectors) or just 1 original style? Youll need to fiddle with a 2 field terminal alternator to work with your 1 blue lead 67 notch wireing harness. Just ground one of the field terminals to the case if you have the 2 field tab alternator, thatll get you back on the 1 wire system.
 
The 37amp we just pulled off had 2 FLD connectors in back (as does our new 50amp), but one of them on the 37amp was just covered up with a rubber boot. Does this mean the ALT wasn't grounded? There is a screw terminal on back that looks like a ground wire could be connected there but nothing was connected to it on the old ALT.
 
Time to get an ohm meter, or battery and a test lamp. See, the problem is that some rebuilders put "non standard" brush holder parts in various alternators to convert them from grounded field (pre-70) to isolated field (70/ later.)

I'd take a test lamp/ meter, check continuity from the exposed brush connection to the frame of the alternator. If you show continuity, the booted connector is already grounded, and you can hook it right up to your 69/ earlier regulator.
 
You should be alright, I upgraded my stock alternator with a 100 amp...then again, I'm running two 12 inch subwoofers and a few other things that need more power
 
green1 said:
Do the madelectric.com amp bypass; install a voltmeter, then do whatever you want.
Click to expand...

I second this 100%. That amp meter was a nightmare to my electrical system, was blowing fuses left and right, deleted it/installed volt meter and so far I've had good luck!
 
Alternator needs 2 fields on opposite "ends" of the rotor to work, like a circuit needs a complete path. Old ones used 1 field as the power in (blue wire terminal) and the other field brush as the ground (internally grounded to the case, but its still a brush, you can take it out and find its uninsulated from the brush to the case). The newer "isolated field" or "2 field terminal" alternators used the 2nd brush (thats usually hard grounded to the case in the old ones) as a "floating ground" that's isolated from the case, brought back to the electronic voltage regulator via the green wire and grounded through that (a variable ground to regulate the output of the alternator) devices case, bolted to the firewall. Careful, there are 2 slip rings in the winding and possible 3 potential brush locations. There is a vertical and horizontal brush that ride on the 2 slip rings that are on "opposite" sides of the rotor. Dont use the same slip ring (the brush locations opposite each other, they tap the same slip ring!) as a power and a ground or floating ground. It wont work, youll be tapping both off one side (slip ring) of the rotor. I believe the old roundback 1 terminal alternator uses the grounded brush on the flat slip ring that is parallel to the parting lines of the case. The power brush rides on the slip ring that is barrel shaped. When you get a brush set, youll see one is shaped like an "L" (flat slip ring contact) and one is shaped like a "C" (power, barrel shaped slip ring contact). So..if you look at the roundback alternator with the mounting bracket pointing up at 12:00, the power terminal is at 12 and the ground terminal is at 9, 3 is the place for the new isolated field brush (or use 9 if 3 is not tapped) Some even have FLD cast in the brush location, even though there is no brush there.
p107076_image_large.jpg
 
Thanks for the responses! Made a mistake though...my old ALT that went out was a 2 field version but again, one of the fields was rubber booted with no wire attached. When I ordered my replacement ALT from Autozone, they sent me a 1 field version and I installed it not even realizing they were different (until now). I have not started up the car yet since installing this new 1 field ALT. Is there anyway I can use this 1 field version even though my previous ALT was a 2 field? I'm guessing so since one of my fields on my previous 2 field version had a rubber boot on it and was not being used....just want to make sure before I melt/burn something.

Is grounding going to be my problem? As Pishta said above, the old 1 field versions were internally grounded to the case and the 2 field versions were ground through the electronic voltage regulator.

Trying to get my car into a cruise/show tomorrow night!!
 
67Dart273 said:
Time to get an ohm meter, or battery and a test lamp. See, the problem is that some rebuilders put "non standard" brush holder parts in various alternators to convert them from grounded field (pre-70) to isolated field (70/ later.)

I'd take a test lamp/ meter, check continuity from the exposed brush connection to the frame of the alternator. If you show continuity, the booted connector is already grounded, and you can hook it right up to your 69/ earlier regulator.
Click to expand...

I already told you how to check this-----either you have one insulated brush or two

Either way, that type unit will work with the early 69/ earlier regulator, all you need to do is ground the remaining connector

IF by chance you "had" the later (70/later) regulator, you MUST have the two isolated field connections, many times (incorrectly) called a "dual field"

A photo of this thing you have with the rubber boot on it would help.
 
67Dart273, thanks for your help/patience. As you can see, I'm a complete noob when it comes to this wiring stuff.

I do have the earlier ('61-69) volt regulator installed (ordered it from Year One, part RX346).

Unfortunately I don't have a picture of the rubber boot I can send you because the core was turned into Autozone the other day. Tried to call tonight to get it back but it was already gone. There was just a rubber boot covering 1 FLD connector at the 3:00 o'clock position as you were looking at the ALT from the back (assuming mounting bolt is at 12:00 o'clock). It had a green wire running from the other FLD that was directly under the mounting bolt and there was a ring terminal with a few cables (including black) running to the BAT post. These were the only wires connected - no separate ground wire.

I've basically connected this new 1 field version up the exact same way as the old 2 field version was. Since the 2 field version wasn't using one of it's FLD connectors via a rubber boot, did this essentially make it a 1 field version?

If this new 1 field version is indeed internally grounded and I run the green wire from the 1 FLD to the volt regulator, will I essentially be grounding the thing twice? If so, does this really matter?

I'm just trying to find a quick solution so I can try and get the car into a cruise tomorrow night and I don't want to burn the thing up.


 
It doesn't matter how many times its grounded or which type alternator it is. If you have just the one green wire to attach to a field terminal, ground the other field terminal. It wont burn anything up either.
 
From your description, it sounds to me like the new one you have should hook right up and work fine.
 
Thanks guys for all the help. Turns out my volt reg was bad which is a little strange because it's less than 6 months old?? Anyway, after replacing that I was good to go for the cruise/show this weekend!
 
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